The three checks in region_intersects() are basically an open-coded version
of resource_overlaps() - so use the real thing.

Also fix typos in comments while at it.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Like Xu <like.xu@linux.intel.com>
Reviewed-by: Yuan Yao <yuan.yao@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: bhelgaas@google.com
Cc: bp@suse.de
Cc: dan.j.williams@intel.com
Cc: jack@suse.cz
Cc: rdunlap@infradead.org
Cc: tiwai@suse.de
Link: http://lkml.kernel.org/r/20190305083432.23675-1-richardw.yang@linux.intel.com
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Currently, kernel/memremap.c contains generic code for supporting
memremap() (CONFIG_HAS_IOMEM) and devm_memremap_pages()
(CONFIG_ZONE_DEVICE). This causes ongoing build maintenance problems as
additions to memremap.c, especially for the ZONE_DEVICE case, need to be
careful about being placed in ifdef guards. Remove the need for these
ifdef guards by moving the ZONE_DEVICE support functions to their own
compilation unit.

Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>