drm/i915/debugfs: switch to kernel types

Mixed C99 and kernel types use is getting ugly.	Prefer kernel types.

sed -i 's/\buint\(8\|16\|32\|64\)_t\b/u\1/g'

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/4d71ed8a432b4121516049334512d35623c8acaa.1547629303.git.jani.nikula@intel.com