msm: kgsl: Do INIT_WORK() just before queueing a deferred mem entry

gpuobj_free_on_fence() is used infrequently enough that it doesn't
make sense to do INIT_WORK() when the memory object is created,
especially if debug objects are enabled because INIT_WORK() will go
off and do a bunch of accounting that we don't need.  Do the
INIT_WORK() just before queueing in those rare cases that this
actually happens.

Change-Id: Ic0dedbad1015883788e12815806e3249a1e09b21
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>