Kconfig: cosmetic: Update description of CMD_SPL_NAND_OFS

The CMD_SPL_NAND_OFS description was a bit misleading, has
been updated.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index ca6de50..d9d26e6 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -325,8 +325,7 @@
 	  command.
 
 config CMD_SPL_NAND_OFS
-	hex "Offset of OS command line args for Falcon-mode NAND boot"
-	depends on CMD_SPL
+	hex "Offset of OS args or dtb for Falcon-mode NAND boot"
 	depends on CMD_SPL && (TPL_NAND_SUPPORT || SPL_NAND_SUPPORT)
 	default 0
 	help