r300: fix unconditional KIL on R300/R400

r300: fix unconditional KIL on R300/R400

  0: KIL -none.1111

Negate is not allowed for texturing opcodes, so the incorrect swizzle
was detected, however later optimization, where we try to rewrite incorrect
swizzles from constant (immediate) registers by adding a new ones with
correct order was interfering and not handling this correctly, so we
ended with

CONST[0] = {    -1.0000    -1.0000    -1.0000    -1.0000 }
  0: KIL const[0].xyz-w;

Even if it would get the swizzle right, texturing opcodes can't read from
constant registers, so just skip it and let this be handled by a later
part which inserts an extra mov instead.

Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>
Reviewed-by: Filip Gawin <filip@gawin.net>
Fixes: a8e1e5b5c2aeb7c2fb4eff2203a026090f0853b9
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22704>