mm/page_isolation: fix tracepoint to mirror check function behavior

Page isolation has not failed if the fin pfn extends beyond the end pfn
and test_pages_isolated checks this correctly.  Fix the tracepoint to
report the same result as the actual check function.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>