io_uring: fix splice_fd_in checks backport typo

The linux-5.10.y backport of commit "io_uring: add ->splice_fd_in checks"
includes a typo: "|" where "||" should be. (The original upstream commit
is fine.)

Fixes: 54eb6211 ("io_uring: add ->splice_fd_in checks")
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org # v5.10
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>