staging: android: ion: Remove check of debug_file

There's no need to check the return value of debug_file for it is just a
debugfs and we will go on the following process if we failed to create
debug_file. So just remove it.

Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>