drm/arm: Replace instances of drm_dev_unref with drm_dev_put.

Replace drm_dev_unref with drm_dev_put as it is more consistent
with kernel coding style. Done using the following semantic
patch by coccinelle.

@r@
expression e;
@@

-drm_dev_unref();
+drm_dev_put();

Signed-off-by: Srishti Sharma <srishtishar@gmail.com>
[split patch into hdlcd and mali-dp versions]
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>