rtc: qpnp-rtc: Add support for suspend to disk

Add support to rtc driver for suspend to disk feature.
Free interrupts during hibernation and re-register them during
resume.

Change-Id: I1b6a454733a3f48674b031cda176e1a943e24c5a
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>