r600/sfn: Don't override a chgr pinning during copy propagation

Fixes: c0b6c59e0 (r600/sfn: Copy propagate into TEX source)
Related: https://gitlab.freedesktop.org/mesa/mesa/-/issues/9998

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25741>

src/gallium/drivers/r600/sfn/sfn_optimizer.cpp

@@ -640,7 +640,8 @@ CopyPropFwdVisitor::propagate_to(RegisterVec4& value, Instr *instr)
 
          value.set_value(i, new_src[i]);
 
-         if (new_src[i]->pin() != pin_fully) {
+         if (new_src[i]->pin() != pin_fully &&
+             new_src[i]->pin() != pin_chgr) {
             if (new_src[i]->pin() == pin_chan)
                new_src[i]->set_pin(pin_chgr);
             else