msm: kgsl: Save a copy of the fence name for syncpoint events

Android native fences have the annoying habit of disappearing before
we are done querying them. Instead of reaching into the fence struct
to find the name for the fence, copy it off at init time and use that
for our various logging needs.

CRs-fixed: 743080
Change-Id: Ic0dedbad21eddf71d5e8a086eea09c5201660f0a
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>