drm/fourcc: Add 64 bpp half float formats

Add 64 bpp 16:16:16:16 half float pixel formats. Each 16 bit component is
formatted in IEEE-754 half-precision float (binary16) 1:5:10
MSb-sign:exponent:fraction form.

This patch attempts to address the feedback provided when 2 of these
formats were previosly proposed:
  https://patchwork.kernel.org/patch/10072545/



v2:
- Fixed cpp (Ville)
- Added detail pixel formatting (Ville)
- Ordered formats in header (Ville)

v5:
- .depth should be 0 for new formats (Maarten)

Cc: Tina Zhang <tina.zhang@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Shashank Sharma <shashank.sharma@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Kevin Strasser <kevin.strasser@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1552437513-22648-2-git-send-email-kevin.strasser@intel.com