pwm: lpss: Support all four PWMs on Intel Broxton

Intel Broxton has similar PWM than Intel Braswell but instead of one it has
four PWMs included in one PCI/ACPI device. This patch adds support for all
the four PWMs and changes the PCI part of the driver to use
'pwm_lpss_bxt_info' instead.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>