msm: sde: Correct rotator irq enable mismatch

This corrects rotator irq enable mismatch by moving enable/disable
sequence to resource allocation/deallocation time.  This will
eliminate race condition between regdma start and wait for done,
which causes unacknowledged rotator interrupt to continuosly trigger
MDSS main interrupt handler, ending in watchdog reset.

CRs-Fixed: 1035411
Change-Id: I597b58b478a35e9c3e3afb1a2ddd20ad87961c1a
Signed-off-by: Alan Kwong <akwong@codeaurora.org>