crc32: make command optional

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/common/cmd_mem.c b/common/cmd_mem.c
index 4b524cf..4f64bda 100644
--- a/common/cmd_mem.c
+++ b/common/cmd_mem.c
@@ -1077,6 +1077,8 @@
 	return 0;
 }
 
+#ifdef CONFIG_CMD_CRC32
+
 #ifndef CONFIG_CRC32_VERIFY
 
 int do_mem_crc (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
@@ -1161,6 +1163,8 @@
 }
 #endif	/* CONFIG_CRC32_VERIFY */
 
+#endif
+
 #ifdef CONFIG_CMD_MD5SUM
 int do_md5sum(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
@@ -1277,6 +1281,8 @@
 	"[.b, .w, .l] addr1 addr2 count"
 );
 
+#ifdef CONFIG_CMD_CRC32
+
 #ifndef CONFIG_CRC32_VERIFY
 
 U_BOOT_CMD(
@@ -1296,6 +1302,8 @@
 
 #endif	/* CONFIG_CRC32_VERIFY */
 
+#endif
+
 U_BOOT_CMD(
 	base,	2,	1,	do_mem_base,
 	"print or set address offset",