comedi: das1800: Add sanity checks for I/O base address

comedi: das1800: Add sanity checks for I/O base address

The "das1800" driver uses an admin-supplied configuration option
(`it->options[0]`) to configure the I/O port base address of a board
compatible with the DAS1800 series.  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 0 to 0x3f0 on
16-byte boundaries.  Some boards have an additional span of up to 0x10
registers at offset 0x400 from the main 0x10 byte region.

Add a sanity check to ensure the device is not configured at an
unsupported base address.  If the main base address is correctly aligned
and within range, then the additional region at offset 0x400 from the
configured base address will naturally be within range and correctly
aligned.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260130170416.49994-16-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>