cifs: fix that return -EINVAL when do dedupe operation

dedupe_file_range operations is combiled into remap_file_range.
But it's always skipped for dedupe operations in function
cifs_remap_file_range.

Example to test:
Before this patch:
  # dd if=/dev/zero of=cifs/file bs=1M count=1
  # xfs_io -c "dedupe cifs/file 4k 64k 4k" cifs/file
  XFS_IOC_FILE_EXTENT_SAME: Invalid argument

After this patch:
  # dd if=/dev/zero of=cifs/file bs=1M count=1
  # xfs_io -c "dedupe cifs/file 4k 64k 4k" cifs/file
  XFS_IOC_FILE_EXTENT_SAME: Operation not supported

Influence for xfstests:
generic/091
generic/112
generic/127
generic/263
These tests report this error "do_copy_range:: Invalid
argument" instead of "FIDEDUPERANGE: Invalid argument".
Because there are still two bugs cause these test failed.
https://bugzilla.kernel.org/show_bug.cgi?id=202935
https://bugzilla.kernel.org/show_bug.cgi?id=202785



Signed-off-by: Xiaoli Feng <fengxiaoli0714@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>