Power: add an API to log wakeup reasons

Add API log_wakeup_reason() and expose it to userspace via sysfs path
/sys/kernel/wakeup_reasons/last_resume_reason

Change-Id: I81addaf420f1338255c5d0638b0d244a99d777d1
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
POWER: fix compile warnings in log_wakeup_reason

Change I81addaf420f1338255c5d0638b0d244a99d777d1 introduced compile
warnings, fix these.

Change-Id: I05482a5335599ab96c0a088a7d175c8d4cf1cf69
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
Power: Add guard condition for maximum wakeup reasons

Ensure the array for the wakeup reason IRQs does not overflow.

Change-Id: Iddc57a3aeb1888f39d4e7b004164611803a4d37c
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
(cherry picked from commit b5ea40cdfcf38296535f931a7e5e7bf47b6fad7f)
power: wakeup_reason: rename irq_count to irqcount

On x86, irq_count conflicts with a declaration in
arch/x86/include/asm/processor.h

Change-Id: I3e4fde0ff64ef59ff5ed2adc0ea3a644641ee0b7
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Power: Changes the permission to read only for sysfs file
/sys/kernel/wakeup_reasons/last_resume_reason

Change-Id: I8ac568a7cb58c31decd379195de517ff3c6f9c65
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>