thermal: remove dangling 'weight_attr' device file

This file isn't getting removed while we unbind a device from thermal
zone. And this causes following messages when the device is registered
again:

WARNING: CPU: 0 PID: 2228 at /home/viresh/linux/fs/sysfs/dir.c:31 sysfs_warn_dup+0x60/0x70()
sysfs: cannot create duplicate filename '/devices/virtual/thermal/thermal_zone0/cdev0_weight'
Modules linked in: cpufreq_dt(+) [last unloaded: cpufreq_dt]
CPU: 0 PID: 2228 Comm: insmod Not tainted 4.2.0-rc3-00059-g44fffd9473eb #272
Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[<c00153e8>] (unwind_backtrace) from [<c0012368>] (show_stack+0x10/0x14)
[<c0012368>] (show_stack) from [<c053a684>] (dump_stack+0x84/0xc4)
[<c053a684>] (dump_stack) from [<c002284c>] (warn_slowpath_common+0x80/0xb0)
[<c002284c>] (warn_slowpath_common) from [<c00228ac>] (warn_slowpath_fmt+0x30/0x40)
[<c00228ac>] (warn_slowpath_fmt) from [<c012d524>] (sysfs_warn_dup+0x60/0x70)
[<c012d524>] (sysfs_warn_dup) from [<c012d244>] (sysfs_add_file_mode_ns+0x13c/0x190)
[<c012d244>] (sysfs_add_file_mode_ns) from [<c012d2d4>] (sysfs_create_file_ns+0x3c/0x48)
[<c012d2d4>] (sysfs_create_file_ns) from [<c03c04a8>] (thermal_zone_bind_cooling_device+0x260/0x358)
[<c03c04a8>] (thermal_zone_bind_cooling_device) from [<c03c2e70>] (of_thermal_bind+0x88/0xb4)
[<c03c2e70>] (of_thermal_bind) from [<c03c10d0>] (__thermal_cooling_device_register+0x17c/0x2e0)
[<c03c10d0>] (__thermal_cooling_device_register) from [<c03c3f50>] (__cpufreq_cooling_register+0x3a0/0x51c)
[<c03c3f50>] (__cpufreq_cooling_register) from [<bf00505c>] (cpufreq_ready+0x44/0x88 [cpufreq_dt])
[<bf00505c>] (cpufreq_ready [cpufreq_dt]) from [<c03d6c30>] (cpufreq_add_dev+0x4a0/0x7dc)
[<c03d6c30>] (cpufreq_add_dev) from [<c02cd3ec>] (subsys_interface_register+0x94/0xd8)
[<c02cd3ec>] (subsys_interface_register) from [<c03d785c>] (cpufreq_register_driver+0x10c/0x1f0)
[<c03d785c>] (cpufreq_register_driver) from [<bf0057d4>] (dt_cpufreq_probe+0x60/0x8c [cpufreq_dt])
[<bf0057d4>] (dt_cpufreq_probe [cpufreq_dt]) from [<c02d03e4>] (platform_drv_probe+0x44/0xa4)
[<c02d03e4>] (platform_drv_probe) from [<c02cead8>] (driver_probe_device+0x174/0x2b4)
[<c02cead8>] (driver_probe_device) from [<c02ceca4>] (__driver_attach+0x8c/0x90)
[<c02ceca4>] (__driver_attach) from [<c02cd078>] (bus_for_each_dev+0x68/0x9c)
[<c02cd078>] (bus_for_each_dev) from [<c02ce2f0>] (bus_add_driver+0x19c/0x214)
[<c02ce2f0>] (bus_add_driver) from [<c02cf490>] (driver_register+0x78/0xf8)
[<c02cf490>] (driver_register) from [<c0009710>] (do_one_initcall+0x8c/0x1d4)
[<c0009710>] (do_one_initcall) from [<c05396b0>] (do_init_module+0x5c/0x1b8)
[<c05396b0>] (do_init_module) from [<c0086490>] (load_module+0xd34/0xed8)
[<c0086490>] (load_module) from [<c0086704>] (SyS_init_module+0xd0/0x120)
[<c0086704>] (SyS_init_module) from [<c000f480>] (ret_fast_syscall+0x0/0x3c)
---[ end trace 3be0e7b7dc6e3c4f ]---

Fixes: db916513 ("thermal: export weight to sysfs")
Acked-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>