drm/msm/sde: add pp 4 and pp 5 interrupts

This change adds the support for additional pingpong interrupts
supported by the hardware, which would be required when layer
mixer 4 and 5 are used

Change-Id: I6172473922898f3c099a9976f20769834ad9f06d
Signed-off-by: Abhijit Kulkarni <kabhijit@codeaurora.org>