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

commit 7314e613 upstream.

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.

Reported-by: Nico Golde <nico@ngolde.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org.>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>