bsp/atsam: Do not disable the WDT

The watchdog timer (WDT) can be configure only once.  Do not touch it in
the BSP since the application may want to use it.

bsps/arm/atsam/net/if_atsam.c

@@ -856,9 +856,6 @@ static void if_atsam_init(void *arg)
 	sc->arpcom.ac_if.if_flags |= IFF_RUNNING;
 	sc->interrupt_number = GMAC_IRQn;
 
-	/* Disable Watchdog */
-	WDT_Disable(WDT);
-
 	/* Enable Peripheral Clock */
 	if ((PMC->PMC_PCSR1 & (1u << 7)) != (1u << 7)) {
 		PMC->PMC_PCER1 = 1 << 7;

bsps/arm/atsam/start/bspstarthooks.c

@@ -152,5 +152,4 @@ void BSP_START_TEXT_SECTION bsp_start_hook_1(void)
   SCB_CleanDCache();
   SCB_InvalidateICache();
   bsp_start_clear_bss();
-  WDT_Disable(WDT);
 }