binder: fix kernel-doc warning of 'file' member

binder: fix kernel-doc warning of 'file' member

The 'struct file' member in 'binder_task_work_cb' definition was renamed
to 'file' between patch versions but its kernel-doc reference kept the
old name 'fd'. Update the naming to fix the W=1 build warning.

Cc: Todd Kjos <tkjos@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501031535.erbln3A2-lkp@intel.com/
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20250106192608.1107362-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>