egl: Handle dri configs with floating point pixel data

egl: Handle dri configs with floating point pixel data

In the case that __DRI_ATTRIB_FLOAT_BIT is set in the dri config, set
EGL_COLOR_COMPONENT_TYPE_FLOAT_EXT in the egl config. Add a field to the
platform driver visual to indicate if it has components that are in floating
point form.

Signed-off-by: Kevin Strasser <kevin.strasser@intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>