spl: spl_mmc: Partition raw boot mode for eMMC

This adds support for providing a partition number instead of a sector for eMMC.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
diff --git a/common/spl/spl_mmc.c b/common/spl/spl_mmc.c
index 3cc05bb..5d688d6 100644
--- a/common/spl/spl_mmc.c
+++ b/common/spl/spl_mmc.c
@@ -196,8 +196,13 @@
 				return;
 		}
 #endif
+#ifdef CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
+		err = mmc_load_image_raw_partition(mmc,
+			CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION);
+#else
 		err = mmc_load_image_raw_sector(mmc,
 			CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR);
+#endif
 		if (!err)
 			return;
 #endif