anv/i965: drop libdrm_intel dependency completely

anv/i965: drop libdrm_intel dependency completely

With Ken's work to drop the library dependency on libdrm_intel, we now
only depend on libdrm for the kernel uapi headers it provides. It
seems like we're better off just embeddeding those headers ourselves,
making the lives of people developping news features tightly
integrated with the kernel a tiny bit easier.

This change also makes it a bit more obvious what cflags/libs are
required by the i915 drivers vs i965, by renaming INTEL_CFLAGS/LIBS
into I915_CFLAGS/LIBS.

Headers were generated from drm-tip on the following commit :

   commit 6d61e70ccc21606ffb8a0a03bd3aba24f659502b
   Merge: 338ffbf7cb5e c0bc126f97fb
   Author: Dave Airlie <airlied@redhat.com>
   Date:   Tue Jun 27 07:24:49 2017 +1000

       Backmerge tag 'v4.12-rc7' into drm-next

v2: Use installed files from the kernel (Daniel Vetter)

v3: Use headers from drm-next rather than drm-tip (Dave/Daniel)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>