staging/mei: Don't check if loop cursor is null

staging/mei: Don't check if loop cursor is null

list_for_each_entry_safe(pos, next, &head, list)
	if (pos) {
		....
	}

This check isn't needed.  The list cursor in a list_for_each()
loop is always a valid pointer

Cc: Oren Weil <oren.jer.weil@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>