Revert "gpiolib: cdev: add gpio_device locking wrapper around gpio_ioctl()"

This reverts commit c0c4e976 which is
commit 1d656bd2.

It breaks the build as it depends on a previously reverted change that
had broken the build.  It can be brought back in the future in an
abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I09be029b347e25dd34e0f4fc16a6accf409f84cf
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>