mesa: Add and use _mesa_has_depth_float_channel

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7410>
(cherry picked from commit fda015023af5d0d2d844d5fde07a8c19e4d8f453)
4 files changed