nir: get ffma support from NIR options for nir_lower_flrp

This also fixes the inverted last parameter of nir_lower_flrp in most drivers.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6599>
14 files changed