target/riscv: Move Guest irqs out of the core local irqs range.

target/riscv: Move Guest irqs out of the core local irqs range.

Qemu maps IRQs 0:15 for core interrupts and 16 onward for
guest interrupts which are later translated to hgiep in
`riscv_cpu_set_irq()` function.

With virtual IRQ support added, software now can fully
use the whole local interrupt range without any actual
hardware attached.

This change moves the guest interrupt range after the
core local interrupt range to avoid clash.

Fixes: 1697837ed9 ("target/riscv: Add M-mode virtual interrupt and IRQ filtering support.")
Fixes: 40336d5b1d ("target/riscv: Add HS-mode virtual interrupt and IRQ filtering support.")
Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20240520125157.311503-3-rkanwal@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>