imx: nandbcb: include long help only when enabled

conditionally include long help text when enabled

Signed-off-by: Parthiban Nallathambi <pn@denx.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/cmd_nandbcb.c b/arch/arm/mach-imx/cmd_nandbcb.c
index 065b814..7811c61 100644
--- a/arch/arm/mach-imx/cmd_nandbcb.c
+++ b/arch/arm/mach-imx/cmd_nandbcb.c
@@ -359,9 +359,11 @@
 	return CMD_RET_USAGE;
 }
 
+#ifdef CONFIG_SYS_LONGHELP
 static char nandbcb_help_text[] =
 	"update addr off|partition len	- update 'len' bytes starting at\n"
 	"	'off|part' to memory address 'addr', skipping  bad blocks";
+#endif
 
 U_BOOT_CMD(nandbcb, 5, 1, do_nandbcb,
 	   "i.MX6 Nand BCB",