vc4: Swap around which src we spill to ra31/rb31.

I wanted to assert that src1 came from a non-unspilled register in shader
validation, and this easily gets us that.  And, as a bonus:

total instructions in shared programs: 93347 -> 92723 (-0.67%)
instructions in affected programs:     60524 -> 59900 (-1.03%)

1 files changed, 4 insertions, 4 deletions

diff --git a/src/gallium/drivers/vc4/vc4_qpu_emit.c b/src/gallium/drivers/vc4/vc4_qpu_emit.c
index 577eb9200f4..99afe4b8798 100644
--- a/src/gallium/drivers/vc4/vc4_qpu_emit.c
+++ b/src/gallium/drivers/vc4/vc4_qpu_emit.c
@@ -117,11 +117,11 @@ fixup_raddr_conflict(struct vc4_compile *c,
                 return;
 
         if (mux0 == QPU_MUX_A) {
-                queue(c, qpu_a_MOV(qpu_rb(31), *src1));
-                *src1 = qpu_rb(31);
+                queue(c, qpu_a_MOV(qpu_rb(31), *src0));
+                *src0 = qpu_rb(31);
         } else {
-                queue(c, qpu_a_MOV(qpu_ra(31), *src1));
-                *src1 = qpu_ra(31);
+                queue(c, qpu_a_MOV(qpu_ra(31), *src0));
+                *src0 = qpu_ra(31);
         }
 }