drm/arm/malidp: use sysfs_emit in show function callback

According to Documentation/filesystems/sysfs.rst, the show() callback
function of kobject attributes should strictly use sysfs_emit() instead
of sprintf() family functions.
Issue identified using the device_attr_show.cocci Coccinelle script.

Signed-off-by: Deepak R Varma <drv@mailo.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/Y9Q5Tt8c9WBDxeyV@ubun2204.myguest.virtualbox.org