msm: RTC driver for Qualcomm MSM7K chipsets

Create a virtual RTC alarm which restricts max suspend sleep time.

Since the QCT RTC alarm doesn't work properly (yet), we need to clamp the
max suspend sleep time if there is an alarm set for the future.  This
ensures that the device will be awake when the virtual RTC alarm needs to
be triggered.

Signed-off-by: San Mehat <san@android.com>