video: Add new aspect ratios for HDMI 2.0

HDMI 2.0/CEA-861-F introduces two new aspect ratios:
- 64:27
- 256:135

This patch adds enumeration for the new aspect ratios
in the existing aspect ratio list.

V2: rebase
V3: rebase
V4: Added r-b from Jose, Ack by Tomi

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Jose Abreu <Jose.Abreu@synopsys.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1476705880-15600-4-git-send-email-shashank.sharma@intel.com