xfs: set xfarray killable sort correctly

xfs: set xfarray killable sort correctly

LOLLM noticed that we *disable* interruptible sorts when the KILLABLE
flag is set.  This is backwards.  Fix the incorrect logic, and rename
the variable to make the connection more obvious.

Cc: stable@vger.kernel.org # v6.10
Fixes: 271557de7cbfde ("xfs: reduce the rate of cond_resched calls inside scrub")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>