ARM: tegra: remove pwfm device from device file

ARM: tegra: remove pwfm device from device file

Remove the tegra_pwfm_device  definition from device files
which is used for registering pwm from board files.

PWM controller is registered from DT unconditionally for all
Tegra SoC and and hence it is not require to register it from
board files.

Change-Id: I6792adbbaf5fc98aaa8859d0a55cd3167635bc62
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-on: http://git-master/r/368147