rtc: qpnp-rtc: Sets RTC time correctly

Currently RTC driver is not setting the RTC time
correctly. RTC H/w needs to be disabled before the
writes, and then re-enabled after the writes are completed.

Change-Id: I4f66a2ea5b8ba52a5e9dcf21da7a09c36b1c9074
CRs-Fixed: 610221
Signed-off-by: Mohit Aggarwal <maggarwa@codeaurora.org>