Currently when we have a blend-to-output color transformation, we have a
16FP shadow buffer representing the blending space. Then we blit from
that to the primary plane fb, which is a regular buffer (fixed-point,
not 16bpc).
The shadow buffer needs to be 16FP because the blending space is linear
with relation to light. So it needs more bits for encoding.
In the next patches we enable the option to offload the blend-to-output
color transformation to KMS, so we'll need the primary plane fb to be
of a 16FP format. In order to do that, we need to be able to find EGL
configs with float-point formats. In this patch we enable that.
Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>