r600/cayman: fix fragcood loading recip generation.

This fixes some hangs seen where the recip_ieee opcodes would
end up split across the wrong slots.

Cc: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/gallium/drivers/r600/r600_shader.c

@@ -3768,7 +3768,7 @@ static int r600_shader_from_tgsi(struct r600_context *rctx,
 				alu.dst.sel = shader->input[ctx.fragcoord_input].gpr;
 				alu.dst.chan = j;
 				alu.dst.write = (j == 3);
-				alu.last = 1;
+				alu.last = (j == 3);
 				if ((r = r600_bytecode_add_alu(ctx.bc, &alu)))
 					return r;
 			}