msm: kgsl: Correct the size of memlist entries in snapshot

The memlist header was correctly updated for 64 bit GPU addressing
but the individual memory entries were still in a 32 bit state of
mind.

Change-Id: Ic0dedbad17a3150739d9644195a653c31d49af17
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>