GPU: drm: fix style errors

This patch fixes style issues in drm_ioctl.c

Signed-off-by: F.A.Sulaiman <asha.16@itfac.mrt.ac.lk>
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Simon Ser <contact@emersion.fr>
Link: https://patchwork.freedesktop.org/patch/msgid/20210828123942.1556-1-asha.16@itfac.mrt.ac.lk