clocksource: armada-370-xp: Register sched_clock after the counter reset

This commit registers the sched_clock _after_ the counter reset
(instead of before). This removes the timestamp 'jump' in kernel
log messages.

Before this change:

[    0.000000] sched_clock: 32 bits at 25MHz, resolution 40ns, wraps every 171798691800ns
[    0.000000] Initializing Coherency fabric
[    0.000000] Aurora cache controller enabled
[    0.000000] l2x0: 16 ways, CACHE_ID 0x00000100, AUX_CTRL 0x1a696b12, Cache size: 1024 kB
[  163.507447] Calibrating delay loop... 1325.05 BogoMIPS (lpj=662528)
[  163.521419] pid_max: default: 32768 minimum: 301
[  163.526185] Mount-cache hash table entries: 512
[  163.531095] CPU: Testing write buffer coherency: ok

After this change:

[    0.000000] sched_clock: 32 bits at 25MHz, resolution 40ns, wraps every 171798691800ns
[    0.000000] Initializing Coherency fabric
[    0.000000] Aurora cache controller enabled
[    0.000000] l2x0: 16 ways, CACHE_ID 0x00000100, AUX_CTRL 0x1a696b12, Cache size: 1024 kB
[    0.016849] Calibrating delay loop... 1325.05 BogoMIPS (lpj=662528)
[    0.030820] pid_max: default: 32768 minimum: 301
[    0.035588] Mount-cache hash table entries: 512
[    0.040500] CPU: Testing write buffer coherency: ok

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Jason Cooper <jason@lakedaemon.net>