drm/i915: Fix checkpatch warns in cursor code

Eliminate checkpatch warnings from intel_cursor.c:
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
WARNING: Possible repeated word: 'by'

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201110175624.3524-2-ville.syrjala@linux.intel.com
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>