The tsc code uses CLOCK_TICK_RATE which on x86
is defined to just be the same as PIT_TICK_RATE.
This patch updates the code use the later
as we want to depecrate and remove the global
CLOCK_TICK_RATE symbol.
Signed-off-by: NDeepak Saxena <dsaxena@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>