msm: kgsl: Fix error handling during drawctxt switch

Currently, separate submissions are made for page table
switch and context switch to the ring buffer. However, if the
page table switch succeeds but the context switch fails,
it can lead to use of wrong page table for drawctxt.
To address this issue, rollback the pagetable to current pagetable.

Also,correctly put the refcount of adreno context during error
cleanup.

Change-Id: I1bb4ee3ebb0ce6ea32f0b6799cfb7fa89c0d09c7
Signed-off-by: Rakesh Naidu Bhaviripudi <[email protected]>