sim: glue: allow bitwise devices to only glue ints

sim: glue: allow bitwise devices to only glue ints

Some Blackfin parts tie a bunch of interrupt lines into a single OR
gate before feeding the result into the SIC.  The glue-or device in
the sim provides a nice way of modeling this exact behavior.  At the
moment though, it requires the device to be mapped into the address
space so that things could write to it directly.  This is not needed
for the Blackfin usage, so make it optional.  Now the glue devices
can be used to simply tie interrupt lines together.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>