MIPS: ath79: Remove unused include <asm/mips_machine.h>

Since commit 3a77e0d7 ("MIPS: ath79: drop machfiles"), this header
is not used anymore.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/ath79/setup.c

@@ -23,7 +23,6 @@
 #include <asm/idle.h>
 #include <asm/time.h>		/* for mips_hpt_frequency */
 #include <asm/reboot.h>		/* for _machine_{restart,halt} */
-#include <asm/mips_machine.h>
 #include <asm/prom.h>
 #include <asm/fw/fw.h>