hw/scsi/lsi53c895a: add timer to scripts processing

hw/scsi/lsi53c895a: add timer to scripts processing

HP-UX 10.20 seems to make the lsi53c895a spinning on a memory location
under certain circumstances. As the SCSI controller and CPU are not
running at the same time this loop will never finish. After some
time, the check loop interrupts with a unexpected device disconnect.
This works, but is slow because the kernel resets the scsi controller.
Instead of signaling UDC, start a timer and exit the loop. Until the
timer fires, the CPU can process instructions which might changes the
memory location.

The limit of instructions is also reduced because scripts running on
the SCSI processor are usually very short. This keeps the time until
the loop is exit short.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Message-ID: <20240229204407.1699260-1-svens@stackframe.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>