MIPS: ath79: drop _machine_restart again

Commit 81424d0 ("MIPS: ath79: Use the reset controller to restart
OF machines") removed setup of _machine_restart on OF machines to use
reset handler in reset controller driver.
While removing remnants of non-OF machines in commit 3a77e0d
("MIPS: ath79: drop machfiles"), this was introduced again, making it
impossible to use additional restart handlers registered through device
tree. Drop setting _machine_restart altogether, and ath79_restart
function, which is no longer used after this.

Fixes: 3a77e0d ("MIPS: ath79: drop machfiles")
Cc: John Crispin <john@phrozen.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/ath79/setup.c

@@ -34,15 +34,6 @@
 
 static char ath79_sys_type[ATH79_SYS_TYPE_LEN];
 
-static void ath79_restart(char *command)
-{
-	local_irq_disable();
-	ath79_device_reset_set(AR71XX_RESET_FULL_CHIP);
-	for (;;)
-		if (cpu_wait)
-			cpu_wait();
-}
-
 static void ath79_halt(void)
 {
 	while (1)
@@ -234,7 +225,6 @@ void __init plat_mem_setup(void)
 
 	detect_memory_region(0, ATH79_MEM_SIZE_MIN, ATH79_MEM_SIZE_MAX);
 
-	_machine_restart = ath79_restart;
 	_machine_halt = ath79_halt;
 	pm_power_off = ath79_halt;
 }