Revert "power: Add option to log time spent in suspend"

This reverts commit df29f3f4.

The suspend_time.c driver has been merged with mainline since 3.11
in kernel/time/timekeeping_debug.c enabled with CONFIG_DEBUG_FS.

Thus I'm reverting the patches to the now duplicative suspend_time.c

Change-Id: I6824d89bcb7d33e7a09ff27da3a3a926c4ba79c0
Signed-off-by: John Stultz <john.stultz@linaro.org>