board: am57xx: Fix missing check for beagle_x15

When beagleboard-X15 is booted, we see the following log:
Unidentified board claims BBRDX15_ in eeprom header

This is because of the missing check for x15 (the default) and reports
an error for a valid board configuration. Fix the same.
Signed-off-by: NNishanth Menon <nm@ti.com>
Reviewed-by: NTom Rini <trini@konsulko.com>
Reviewed-by: NLokesh Vutla <lokeshvutla@ti.com>

board/ti/am57xx/board.c

@@ -338,7 +338,9 @@ static void setup_board_eeprom_env(void)
 	if (rc)
 		goto invalid_eeprom;
 
-	if (board_is_am572x_evm())
+	if (board_is_x15())
+		name = "beagle_x15";
+	else if (board_is_am572x_evm())
 		name = "am57xx_evm";
 	else if (board_is_am572x_idk())
 		name = "am572x_idk";