dev-arm: Fix DTB autogen for HDLcd

dev-arm: Fix DTB autogen for HDLcd

The HDLcd was wrongly reporting the hardcoded IRQ=63 as the interrupt
number during DTB autogeneration. This is because the DTS is using 63.
However that corresponds to the SPI offset; the gem5 helper is
instead expecting the global IRQ number = 32 + SPI offset

Change-Id: I9e82360843eacb13cef5ddd2e28d2f3ef3147335
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/31940
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>