hw/riscv: virt: Make few IMSIC macros and functions public

hw/riscv: virt: Make few IMSIC macros and functions public

Some macros and static function related to IMSIC are defined in virt.c.
They are required in virt-acpi-build.c. So, make them public.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20231218150247.466427-5-sunilvl@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>