drivers: qcom: system_pm: Save/restore GICD registers at system sleep

Some of the GICD registers could be read in and stored as zeros if an
intterupt is triggered around the same time as the system sleep. The
pending state of the interrupt would be latched but the configuration
registers for the interrupt is reset. To ensure that the interrupt
triggers, restore the interrupts configuration around System sleep
notification.

Change-Id: Ib04720241e8fa4382383bd08897c4e19aaaded8c
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>