libdrm: upgrade to 2.4.40

libdrm: upgrade to 2.4.40

Other changes:
 * removed a backported patch;
 * activated libdrm-omap helper layer which is needed by the latest
   xf86-video-omap xorg driver;
 * split libdrm-drivers package into libdrm-radeon, libdrm-nouveau and
   libdrm-omap, libdrm-intel and libdrm-exynos;

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>