hw/riscv: virt: Fix the value of "riscv, ndev" in the dtb

hw/riscv: virt: Fix the value of "riscv, ndev" in the dtb

Commit 28d8c281200f ("hw/riscv: virt: Add optional AIA IMSIC support to virt machine")
changed the value of VIRT_IRQCHIP_NUM_SOURCES from 127 to 53, which
is VIRTIO_NDEV and also used as the value of "riscv,ndev" property
in the dtb. Unfortunately this is wrong as VIRT_IRQCHIP_NUM_SOURCES
should include interrupt source 0 but "riscv,ndev" does not.

While we are here, we also fix the comments of platform bus irq range
which is now "64 to 96", but should be "64 to 95", introduced since
commit 1832b7cb3f64 ("hw/riscv: virt: Create a platform bus").

Fixes: 28d8c281200f ("hw/riscv: virt: Add optional AIA IMSIC support to virt machine")
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221211030829.802437-13-bmeng@tinylab.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>