net/wireless: use generic_file_llseek in debugfs

The default llseek operation is changing from
default_llseek to no_llseek, so all code relying on
the current behaviour needs to make that explicit.

The wireless driver infrastructure and some of the drivers
make use of generated debugfs files, so they cannot
be converted by our script that automatically determines
the right operation.

All these files use debugfs and they typically rely
on simple_read_from_buffer, so the best llseek operation
here is generic_file_llseek.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org