msm: kgsl: Fix gpudev NULL dereference in adreno_remove

In adreno_remove() there is possibility of dereference of gpudev
without NULL check. Fix this by getting gpudev after adreno_dev
NULL check.

CRs-Fixed: 993267
Change-Id: I17d8b4ba2c74a787a065dbdb0ac88d065605fcb1
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>