imx: kontron-sl-mx8mm: Remove custom board_boot_order() workaround

Nowadays detecting the SPI NOR as boot device from the ROMAPI is
fixed and works even if the SPI NOR is used as fallback boot device.

Therefore we don't need this workaround anymore.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Fabio Estevam <festevam@denx.de>
diff --git a/board/kontron/sl-mx8mm/spl.c b/board/kontron/sl-mx8mm/spl.c
index c379d37..2a562f4 100644
--- a/board/kontron/sl-mx8mm/spl.c
+++ b/board/kontron/sl-mx8mm/spl.c
@@ -238,25 +238,3 @@
 
 	board_init_r(NULL, 0);
 }
-
-void board_boot_order(u32 *spl_boot_list)
-{
-	u32 bootdev = spl_boot_device();
-
-	/*
-	 * The default boot fuse settings use the SD card (MMC2) as primary
-	 * boot device, but allow SPI NOR as a fallback boot device.
-	 * We can't detect the fallback case and spl_boot_device() will return
-	 * BOOT_DEVICE_MMC2 despite the actual boot device being SPI NOR.
-	 * Therefore we try to load U-Boot proper vom SPI NOR after loading
-	 * from MMC has failed.
-	 */
-	spl_boot_list[0] = bootdev;
-
-	switch (bootdev) {
-	case BOOT_DEVICE_MMC1:
-	case BOOT_DEVICE_MMC2:
-		spl_boot_list[1] = BOOT_DEVICE_SPI;
-		break;
-	}
-}