imx9: imx93_evk: drop unused macro

Drop unused macro

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/include/configs/imx93_evk.h b/include/configs/imx93_evk.h
index 7b7bef3..2705587 100644
--- a/include/configs/imx93_evk.h
+++ b/include/configs/imx93_evk.h
@@ -131,8 +131,6 @@
 #define PHYS_SDRAM                      0x80000000
 #define PHYS_SDRAM_SIZE			0x80000000 /* 2GB DDR */
 
-#define CFG_SYS_FSL_USDHC_NUM	2
-
 /* Using ULP WDOG for reset */
 #define WDOG_BASE_ADDR          WDG3_BASE_ADDR