sh: mach-dreamcast: Handle virq offset in cascaded IRQ demux

sh: mach-dreamcast: Handle virq offset in cascaded IRQ demux

commit 3d20f7a6eb76afdf9d4ad9cb864c2e2da9c38e1f upstream.

Take into account the virq offset when translating cascaded interrupts.

Fixes: a8ac2961148e8c72 ("sh: Avoid using IRQ0 on SH3 and SH4")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/7d0cb246c9f1cd24bb1f637ec5cb67e799a4c3b8.1688908227.git.geert+renesas@glider.be
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>