VAX: Set CPU model correctly on each boot

Previously the CPU model was only being set when the CPU ROM was
implicitly loaded from the internal ROM image at boot time.  Other
loading of ROM code never set the configured model correctly.

VAX/vax_sysdev.c

@@ -1727,8 +1727,8 @@ if (*rom == 0) {                                        /* no boot? */
     r = cpu_load_bootcode (BOOT_CODE_FILENAME, BOOT_CODE_ARRAY, BOOT_CODE_SIZE, TRUE, 0);
     if (r != SCPE_OK)
         return r;
-    rom_wr_B (ROMBASE+4, sys_model ? 1 : 2);            /* Set Magic Byte to determine system type */
     }
+rom_wr_B (ROMBASE+4, sys_model ? 1 : 2);                /* Set Magic Byte to determine system type */
 sysd_powerup ();
 return SCPE_OK;
 }