r300: use ssa-like form for gl_FragCoord transformation

Lots of backend code will be simpler if we have ssa-like (as much as we
can have with vec4), so just don't reuse registers here.

Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>
Reviewed-by: Filip Gawin <None>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33066>
1 file changed