ColdFire: Update the lds file for M54418TWR board.

The M54418TWR lds file  need to update since commit:

8b493a52

common: Discard the __u_boot_cmd section

The command declaration now uses the new LG-array method to generate
list of commands. Thus the __u_boot_cmd section is now superseded and
redundant and therefore can be removed. Also, remove externed symbols
associated with this section from include/command.h .
Signed-off-by: NJason Jin <Jason.jin@freescale.com>

board/freescale/m54418twr/u-boot.lds

@@ -66,9 +66,11 @@ SECTIONS
   PROVIDE (edata = .);
 
   . = .;
-  __u_boot_cmd_start = .;
-  .u_boot_cmd : { *(.u_boot_cmd) }
-  __u_boot_cmd_end = .;
+
+  . = ALIGN(4);
+  .u_boot_list : {
+	#include <u-boot.lst>
+  }
 
   . = .;
   __start___ex_table = .;