sound: oss/pas2: Remove CLOCK_TICK_RATE dependency from PAS16 driver

Update the PAS16 driver to use PIT_TICK_RATE instead
of the more generic CLOCK_TICK_RATE as the two are
equivalent on X86 and we want to depecrate the later.

Signed-off-by: Deepak Saxena <dsaxena@linaro.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>