sched/debug: Make sysrq prints of sched debug data optional

Calls to sysrq_sched_debug_show() can yield rather verbose output
which
contributes to log spew and, under heavy load, may increase
the chances
of a watchdog bark.

Make printing of this data optional with the
introduction of a
new Kconfig, CONFIG_SYSRQ_SCHED_DEBUG.

Change-Id:
I5f54d901d0dea403109f7ac33b8881d967a899ed
Signed-off-by: Matt Wagantall
<mattw@codeaurora.org>

idea is taken here -
https://github.com/jrior001/android_kernel_samsung_d2/commit/ce353820963a3617cdb16561317b65918732ad89