imx: spl: implement spl_boot_device for i.MX8M

Implement spl_boot_device for i.MX8M.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Reviewed-by: Stefano Babic <sbabic@denx.de>

arch/arm/mach-imx/spl.c

@@ -97,8 +97,8 @@ u32 spl_boot_device(void)
 	return BOOT_DEVICE_NONE;
 }
 
-#elif defined(CONFIG_MX7)
-/* Translate iMX7 boot device to the SPL boot device enumeration */
+#elif defined(CONFIG_MX7) || defined(CONFIG_MX8M)
+/* Translate iMX7/MX8M boot device to the SPL boot device enumeration */
 u32 spl_boot_device(void)
 {
 	enum boot_device boot_device_spl = get_boot_device();
@@ -115,11 +115,13 @@ u32 spl_boot_device(void)
 		return BOOT_DEVICE_NAND;
 	case SPI_NOR_BOOT:
 		return BOOT_DEVICE_SPI;
+	case USB_BOOT:
+		return BOOT_DEVICE_USB;
 	default:
 		return BOOT_DEVICE_NONE;
 	}
 }
-#endif /* CONFIG_MX6 || CONFIG_MX7 */
+#endif /* CONFIG_MX6 || CONFIG_MX7 || CONFIG_MX8M */
 
 #ifdef CONFIG_SPL_USB_GADGET_SUPPORT
 int g_dnl_bind_fixup(struct usb_device_descriptor *dev, const char *name)