Staging: memrar: fix printk format warning

Fix printk format warning in memrar:
drivers/staging/memrar/memrar_handler.c:393: warning: format '%u' expects type 'unsigned int', but argument 4 has type 'size_t'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Ossama Othman <ossama.othman@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>