Add support for the two- and four-port variants of XR21V1410.
Use the interface number of each control interface (e.g. 0, 2, 4, 6) to
derive the zero-based channel index:
XR21V1410 0
XR21V1412 0, 1
XR21V1414 0, 1, 2, 3
Note that the UART registers reside in separate blocks per channel,
while the UART Manager functionality is implemented using per-channel
registers.
Signed-off-by: Johan Hovold <johan@kernel.org>
23b7998e81