kernel: gtod: Add MSM-specific user-accessible timers

Enable MSM-specific timers to be readable from user-space.
This allows implementation of a higher-performance
gettimeofday in user-space.

Change-Id: I1f322b5396ee335b10aeb81c681593621d151176
Signed-off-by: Brent DeGraaf <bdegraaf@codeaurora.org>