svga: simplify surface propagation code in svga_set_framebuffer_state()
svga: simplify surface propagation code in svga_set_framebuffer_state()

Rewrite the comment too.

Reviewed-by: Neha Bhende <faec1a32a2d2624ef91f92ce8eed261ff4162c00@vmware.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler