[COMMON] kernel: watchdog: detect hard lockups without NMIs using secondary cpus

[COMMON] kernel: watchdog: detect hard lockups without NMIs using secondary cpus

Emulate NMIs on systems where they are not available by using timer
interrupts on other cpus.  Each cpu will use its softlockup hrtimer
to check that the next cpu is processing hrtimer interrupts by
verifying that a counter is increasing.

This patch is useful on systems where the hardlockup detector is not
available due to a lack of NMIs, for example most ARM SoCs.
Without this patch any cpu stuck with interrupts disabled can
cause a hardware watchdog reset with no debugging information,
but with this patch the kernel can detect the lockup and panic,
which can result in useful debugging info.

Change-Id: I0363ee438625863f466dd07ef4b14d8094822840
Signed-off-by: Hyunki Koo <hyunki00.koo@samsung.com>
Signed-off-by: Changki Kim <changki.kim@samsung.com>