msm: kgsl: Minor cleanups for kgsl bus probe

The KGSL bus probe was not quite resilient for a deferred probe. Move
a memory allocation to devm and make sure that the interconnect handle
is properly put away on failure.

Change-Id: Ic0dedbad261c483a157161a43da0b54459ed46ff
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>