i965: Allow 8x MSAA on >= 64bpp formats on Gen8+.
i965: Allow 8x MSAA on >= 64bpp formats on Gen8+.

See commit 3b0279a69 - this restriction is documented in the "Surface
Format" field of RENDER_SURFACE_STATE.

Looking at newer documentation, this restriction appears to exist on
Haswell, but no longer applies on Gen8+.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Ben Widawsky <73675debcd8a436be48ec22211dcf44fe0df0a64@bwidawsk.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler