xilinx: Define only mmc devnum not partition

The commit 53b406369e9d ("DFU: Check the number of arguments and argument
string strictly") added strict control over string that 0:1 partition
definition is not valid anymore that's why use only device number without
partition ID. Device is specified by 2nd parameter and partition by 3rd.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/840eca944f4f2abeeb63b5d724f9ba5fe9a9213b.1660055571.git.michal.simek@amd.com
diff --git a/board/xilinx/zynq/board.c b/board/xilinx/zynq/board.c
index 3ab63fa..c96433b 100644
--- a/board/xilinx/zynq/board.c
+++ b/board/xilinx/zynq/board.c
@@ -176,7 +176,7 @@
 	switch ((zynq_slcr_get_boot_mode()) & ZYNQ_BM_MASK) {
 	case ZYNQ_BM_SD:
 		snprintf(buf, DFU_ALT_BUF_LEN,
-			 "mmc 0:1=boot.bin fat 0 1;"
+			 "mmc 0=boot.bin fat 0 1;"
 			 "%s fat 0 1", CONFIG_SPL_FS_LOAD_PAYLOAD_NAME);
 		break;
 	case ZYNQ_BM_QSPI: