ARM: at91: Don't invoke spl_boot_device() twice

Since the spl_boot_mode() is now passed the boot device to boot from,
make use of it instead of inquiring for the boot device again. This
allows board_boot_order() to function correctly.
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Andreas Bießmann <andreas.devel@googlemail.com>
Reviewed-by: NAndreas Bießmann <andreas@biessmann.org>

arch/arm/mach-at91/spl.c

@@ -77,7 +77,7 @@ u32 spl_boot_device(void)
 
 u32 spl_boot_mode(const u32 boot_device)
 {
-	switch (spl_boot_device()) {
+	switch (boot_device) {
 #ifdef CONFIG_SYS_USE_MMC
 	case BOOT_DEVICE_MMC1:
 	case BOOT_DEVICE_MMC2: