staging/lustre/llite: remove ll_file_get_iov_count

It exactly copies generic_segment_checks() except wrongly calling
access_ok(VERIFY_READ) for aio read range. Drop it and just call
generic_segment_checks() instead.

Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>