Fix a few incorrectly checked [io_]remap_pfn_range() calls

Nico Golde reports a few straggling uses of [io_]remap_pfn_range() that
really should use the vm_iomap_memory() helper.  This trivially converts
two of them to the helper, and comments about why the third one really
needs to continue to use remap_pfn_range(), and adds the missing size
check.

CRs-Fixed: 570735
Change-Id: I927a67ea80fea5ed706749ead9defb1e72633952
Reported-by: Nico Golde <nico@ngolde.de>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org.>
Git-commit: 7314e613
Git-repo: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git


[pratibha@codeaurora.org:resolve trivial merge conflicts]
Signed-off-by: Pratibhasagar V <pratibha@codeaurora.org>

Signed-off-by: Ed Tam <etam@google.com>