imx_watchdog: add weak attribute to reset_cpu function

This allows to overwrite reset_cpu function in case a board level
reset is preferred (e.g. through PMIC).

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>

drivers/watchdog/imx_watchdog.c

@@ -39,7 +39,7 @@ void hw_watchdog_init(void)
 }
 #endif
 
-void reset_cpu(ulong addr)
+void __attribute__((weak)) reset_cpu(ulong addr)
 {
 	struct watchdog_regs *wdog = (struct watchdog_regs *)WDOG1_BASE_ADDR;