arm64: zynqmp: Check firmware node when driver is enabled

ZynqMP mini configurations works without PMU firmware that's why there is
no reason to enable the driver and check if it was probed properly.

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

board/xilinx/zynqmp/zynqmp.c

@@ -341,11 +341,13 @@ static int multi_boot(void)
 
 int board_init(void)
 {
+#if defined(CONFIG_ZYNQMP_FIRMWARE)
 	struct udevice *dev;
 
 	uclass_get_device_by_name(UCLASS_FIRMWARE, "zynqmp-power", &dev);
 	if (!dev)
 		panic("PMU Firmware device not found - Enable it");
+#endif
 
 #if defined(CONFIG_SPL_BUILD)
 	/* Check *at build time* if the filename is an non-empty string */