The new fscache IO API removes the following invalidation related
older APIs: fscache_uncache_all_inode_pages, fscache_uncache_page,
and fscache_wait_on_page_write.  Update various code paths to the
new API which only requires we wait for PG_fscache which indicates
fscache IO in progress on the page.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>