r600g: fix constant buffer fetches

Somebody forgot to do this. It was uncovered by recent st/mesa changes.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82139

Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Tested-by: Andreas Boll <andreas.boll.dev@gmail.com>

src/gallium/drivers/r600/r600_shader.c

@@ -1019,6 +1019,7 @@ static int tgsi_split_constant(struct r600_shader_ctx *ctx)
 				alu.src[0].sel = ctx->src[i].sel;
 				alu.src[0].chan = k;
 				alu.src[0].rel = ctx->src[i].rel;
+				alu.src[0].kc_bank = ctx->src[i].kc_bank;
 				alu.dst.sel = treg;
 				alu.dst.chan = k;
 				alu.dst.write = 1;