[DRIVERS] Differentiate between memmaped & I/O Mapped device

Check the address_type field in DTS to differentiate between
memory mapped and IO mapped device. Then call the devtree
functions accordingly.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Add address type for 8250 type UART

Mark address type as IO.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>