msm: kgsl: fix sync file error handling

We need to call put_unused_fd() on failure, but only if
a file hasn't been stored into the fd yet. This function
wasn't called from kgsl_ioctl_syncsource_create_fence()
and was called incorrectly from kgsl_add_fence_event().
Reorder our sync_fence_install() calls to happen after
all possible failures so that error cleanup will be
correct.

Change-Id: I0e7bb459f2acc010446ac5e5b3b72c8b16cce079
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>
Signed-off-by: Sudeep Yedalapure <sudeepy@codeaurora.org>