comedi: rti800: Add sanity checks for I/O base address

comedi: rti800: Add sanity checks for I/O base address

The "rti800" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of a RTI-800
or RTI-815 board.  It currently allows any base address to be configured
but the hardware only supports base addresses (configured by on-board
DIP switches) in the range 0 to 0x3F0 on 16-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/20260130170416.49994-45-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>