msm: kgsl: fix size checking in adreno_find_region

This function is supposed to return the memdesc that
contains the range gpuaddr to gpuaddr + size. One of the
lookups was using sizeof(unsigned int) instead of size,
which could cause false positive results from this function
and possibly kernel panics in the snapshot or postmortem
code, which rely on it to do bounds checking for them.

Change-Id: I65dc48108f2010887e620a252a6afbd88473ac6e
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>