devmem: add range_is_allowed() check to mmap of /dev/mem

Earlier patch that introduced CONFIG_NONPROMISC_DEVMEM, did the
range_is_allowed() check only for read and write. Add range_is_allowed()
check to mmap of /dev/mem as well.

Changes the paramaters of range_is_allowed() to pfn and size to handle
more than 32 bits of physical address on 32 bit arch cleanly.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>