cmd_mem: localize state variables

These "last" variables aren't used outside of this file, so add static.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>

common/cmd_mem.c

@@ -48,9 +48,9 @@ static int mod_mem(cmd_tbl_t *, int, int, int, char * const []);
 /* Display values from last command.
  * Memory modify remembered values are different from display memory.
  */
-uint	dp_last_addr, dp_last_size;
-uint	dp_last_length = 0x40;
-uint	mm_last_addr, mm_last_size;
+static uint	dp_last_addr, dp_last_size;
+static uint	dp_last_length = 0x40;
+static uint	mm_last_addr, mm_last_size;
 
 static	ulong	base_address = 0;