msm: mdss: add sysfs to generate the misr crc during interrupts

This change add a sysfs node to enable the misr crc generation
in batch mode. Once this is enabled, driver will collect the
crc numbers during each of the interfaces interrupt,
vsync interrupt for video mode panels and ping pong done
for cmd mode panels.

To enable/disable the crc generation, respectively:
echo 1 > /sys/class/graphics/fb0/msm_misr_en
echo 0 > /sys/class/graphics/fb0/msm_misr_en
To collect the last crc generated:
cat /sys/class/graphics/fb0/msm_misr_en
To enable the ftrace to collect the crc for all frames:
echo 1 > <debugfs>/tracing/events/mdss/mdp_misr_crc/enable

CRs-Fixed: 964076
Change-Id: I47fb47b772aef097bc9af3b58a6c79565bcdc872
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>