of_iomap and request_mem_region

of_iomap doesn't implicitly do a request_mem_region().  How should
request_mem_region() be handled? When using of_iomap you don't get the
length of the region back so it isn't easy to call request_mem_region.

What about adding a third param to of_iomap for the driver name? If it
is non-null also do the request region. If it is null check to make
sure the region has already be requested.

-- 
Jon Smirl
jonsmirl@gmail.com