Improve imx31 interrupt code for PMIC and GPIO

Fix stuff that was bugging me about the way I did it at first.

While messing around I found RDS code wasn't masking its GPIO
ISR as it should, which might lead to two different interrupts
messing with the static data.

Change-Id: I54626809ea3039a842af0cc9e3e42853326c4193
19 files changed