drm/i915/glk: Add MODULE_FIRMWARE for Geminilake

As the Geminilake firmware is now merged to linux-firmware.git
use MODUE_FIRMWARE to load the firmware.

This removes the error message in the dmesg log:

    i915 0000:00:02.0: Direct firmware load for
        i915/glk_dmc_ver1_04.bin failed with error -2
    i915 0000:00:02.0: Failed to load DMC firmware
        i915/glk_dmc_ver1_04.bin. Disabling runtime power management.
    i915 0000:00:02.0: DMC firmware homepage:
        https://01.org/linuxgraphics/downloads/firmware



and now shows that the firmware has correctly loaded:

    [drm] Finished loading DMC firmware i915/glk_dmc_ver1_04.bin (v1.4)

Signed-off-by: Ian W MORRISON <ianwmorrison@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180411044213.383-1-ianwmorrison@gmail.com