Sparse reports a warning at queue_pages_pmd()

context imbalance in queue_pages_pmd() - unexpected unlock

The root cause is the missing annotation at queue_pages_pmd()
Add the missing __releases(ptl)
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-8-jbi.octave@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>