nouveau: make color/depth bpp match for pre-nv10 chips
nouveau: make color/depth bpp match for pre-nv10 chips

This avoids generating fbconfigs whose winsys framebuffers will be
incomplete (see nouveau_check_framebuffer_complete).

Signed-off-by: Ilia Mirkin <bcbbb7aa705ec3a5fc5824c01a845186c3d62fca@alum.mit.edu>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler