xilinx: common: Fix MAC address read from EEPROM

The upper-to-lowercase character conversion now avoids altering the
MAC address field. In the previous version, this alteration corrupted
the MAC address.

Signed-off-by: Petr Zejdl <petr.zejdl@cern.ch>
Link: https://lore.kernel.org/r/20240404114422.2905194-1-petr.zejdl@cern.ch
Signed-off-by: Michal Simek <michal.simek@amd.com>
diff --git a/board/xilinx/common/board.c b/board/xilinx/common/board.c
index f511701..b47d2d2 100644
--- a/board/xilinx/common/board.c
+++ b/board/xilinx/common/board.c
@@ -105,10 +105,14 @@
 	for (i = 0; i < size; i++) {
 		byte = eeprom[i];
 
-		/* Remove all non printable chars but ignore MAC address */
-		if ((i < offsetof(struct xilinx_legacy_format, eth_mac) ||
-		     i >= offsetof(struct xilinx_legacy_format, unused1)) &&
-		     (byte < '!' || byte > '~')) {
+		/* Ignore MAC address */
+		if (i >= offsetof(struct xilinx_legacy_format, eth_mac) &&
+		    i < offsetof(struct xilinx_legacy_format, unused1)) {
+			continue;
+		}
+
+		/* Remove all non printable chars */
+		if (byte < '!' || byte > '~') {
 			eeprom[i] = 0;
 			continue;
 		}