drm/vkms: replace macro in vkms_release()

Replace macro in vkms_release()

Signed-off-by: Beatriz Martins de Carvalho <martinsdecarvalhobeatriz@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210706154510.224695-1-martinsdecarvalhobeatriz@gmail.com