soc: swr-mstr: Store enabled interrupts information in master data

Store interrupt mask variable in master private data to
indicate the interrupts which are currently enabled. This
is to avoid reading interrupt enable register, which varies
on hardware version, for knowing the interrupt enabled info.

Change-Id: Ic990decd1b1112a1ad2a6af0d9b42269fe4e1b4c
Signed-off-by: Ramprasad Katkam <katkam@codeaurora.org>