drm/malidp: Fix smart layer when doing pm_suspend/resume

Smart layer enable rectangles is set to 1 when the driver is probed,
however when doing pm_suspend the value is lost and it's not set again
making the SMART_LAYER unusable, fix that by initializing the number
of rectangles everytime we do a plane update.

Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>