comedi: dt2815: Add sanity checks for I/O base address

comedi: dt2815: Add sanity checks for I/O base address

The "dt2815" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of a DT2815
board.  It currently allows any base address to be configured but the
hardware only supports base addresses (configured by an on-board DIP
switch) in the range 0x200 to 0x3fe on 2-byte boundaries.

Add a sanity check to ensure the device is not configured at an
unsupported base address.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260130170416.49994-23-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>