msm: kgsl: Free our global memory in adreno_remove

Free device firmware copies and command streams that are used to
quickly program the GPU. Free this data in adreno_remove rather than
when the ringbuffer is closed.

Change-Id: I125f03a526e0f165a54e8e868ecd4d181d80796c
Signed-off-by: Carter Cooper <ccooper@codeaurora.org>