ir3/cp: ignore alias sources for sam.s2en

ir3_cp asserts that the first source of a sam.s2en is a collect which
isn't necessarily true after creating alias registers.

Signed-off-by: Job Noorman <jnoorman@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34397>

src/freedreno/ir3/ir3_cp.c

@@ -566,7 +566,8 @@ instr_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr)
     */
    if (is_tex(instr) && (instr->flags & IR3_INSTR_S2EN) &&
        !(instr->flags & IR3_INSTR_B) &&
-       !(ir3_shader_debug & IR3_DBG_FORCES2EN)) {
+       !(ir3_shader_debug & IR3_DBG_FORCES2EN) &&
+       !(instr->srcs[0]->flags & IR3_REG_ALIAS)) {
       /* The first src will be a collect, if both of it's
        * two sources are mov from imm, then we can
        */