drm/atomic: Don't try to free a NULL state
drm/atomic: Don't try to free a NULL state

Consistently with other free functions, handle the NULL case without
oopsing.

Cc: e29a046d56d20477d35c94c7163db1056870c39f@lists.freedesktop.org
Signed-off-by: Ander Conselvan de Oliveira <71330eafc99ba196752d2b2af84b34019e4104c2@intel.com>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs