drm/radeon/kms: Fix NULL ptr dereference
drm/radeon/kms: Fix NULL ptr dereference

radeon_atombios_fini might be call while there is not valid
atombios structure allocated, thus test for a not null ptr
before trying to access this structure.

Signed-off-by: Jerome Glisse <0620d428a1bd3756b1319066bf466b3b8be0b2b2@redhat.com>
Signed-off-by: Dave Airlie <f2295d84e358395675bc8031be58672073ae065e@linux.ie>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas