UBUNTU: SAUCE: (no-up) i915: Remove MODULE_FIRMWARE statements for unreleased firmware

BugLink: http://bugs.launchpad.net/bugs/1626740
Intel has added MODULE_FIRMWARE statements to i915 which refer to
firmware files that they have not yet pushed out to upstream
linux-firmware. This causes the following warnings when
generating the initrd:

 W: Possible missing firmware /lib/firmware/i915/kbl_guc_ver9_14.bin for module i915
 W: Possible missing firmware /lib/firmware/i915/bxt_guc_ver8_7.bin for module i915

This firmware is clearly optional, and the warnings have been
generating a lot of confusion for users. Remove the offending
MODULE_FIRMWARE statements until Intel makes these files
available.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>