vfs: _user_ioctl: any buffer value is allowed for some ops.

some ops want an integer value instead of a pointer as arg parameter ( #15058 ).

http://pubs.opengroup.org/onlinepubs/9699919799/functions/ioctl.html clearly specifies that:
"The type of arg depends upon the particular control request, but it shall be either an
integer or a pointer to a device-specific data structure."

add a test for functions which should return ENOTTY as errno.

Change-Id: I4a98af73b17c79c3460123d3794ee866f8719898
Reviewed-on: https://review.haiku-os.org/c/1447
Reviewed-by: waddlesplash <waddlesplash@gmail.com>