i965: Move BAD_FILE from the beginning of enum register_file.

I'm going to begin using brw_reg's file field in backend_reg and its
derivatives, and in order to keep the hardware value for ARF as 0, we
have to do something different.

Reviewed-by: Emil Velikov <emil.velikov@collabora.co.uk>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/drivers/dri/i965/brw_shader.h

@@ -39,13 +39,13 @@
 #define MAX_VGRF_SIZE 16
 
 enum PACKED register_file {
-   BAD_FILE,
    GRF,
    MRF,
    IMM,
    HW_REG, /* a struct brw_reg */
    ATTR,
    UNIFORM, /* prog_data->params[reg] */
+   BAD_FILE,
 };
 
 #ifdef __cplusplus