arm: zynq: Wire watchdog internals

Watchdog is only enabled in full u-boot. Adoption for SPL should be also
done because that's the right place where watchdog should be enabled.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/Kconfig

@@ -762,6 +762,7 @@ config ARCH_ZYNQ
 	select SUPPORT_SPL
 	select OF_CONTROL
 	select SPL_BOARD_INIT if SPL
+	select BOARD_EARLY_INIT_F if WDT
 	select SPL_OF_CONTROL if SPL
 	select DM
 	select DM_ETH if NET