Linux 4.6 compat: PAGE_CACHE_SIZE removal

Linux 4.6 compat: PAGE_CACHE_SIZE removal

As described in torvalds/linux@4a2d057e the macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were originally introduced
to make it possible to add bigger chunks to the page cache.  This
never panned out and it has therefore been removed from the kernel.

ZFS has been updated to use the PAGE_{SIZE,SHIFT,MASK,ALIGN} macros
and calls to page_cache_release() have been replaced with put_page().

There was no need to introduce a configure check for this because
these interfaces have existed for a very long time.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Closes #4489