test_xarray: fix failure in check_pause when CONFIG_XARRAY_MULTI is not defined

test_xarray: fix failure in check_pause when CONFIG_XARRAY_MULTI is not defined

In case CONFIG_XARRAY_MULTI is not defined, xa_store_order can store a
multi-index entry but xas_for_each can't tell sbiling entry from valid
entry.  So the check_pause failed when we store a multi-index entry and
wish xas_for_each can handle it normally.  Avoid to store multi-index
entry when CONFIG_XARRAY_MULTI is disabled to fix the failure.

Link: https://lkml.kernel.org/r/20250213163659.414309-1-shikemeng@huaweicloud.com
Fixes: c9ba5249ef8b ("Xarray: move forward index correctly in xas_pause()")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/r/CAMuHMdU_bfadUO=0OZ=AoQ9EAmQPA4wsLCBqohXR+QCeCKRn4A@mail.gmail.com
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>