target/riscv: use isa_ext_update_enabled() in init_max_cpu_extensions()

target/riscv: use isa_ext_update_enabled() in init_max_cpu_extensions()

Before adding support to detect if an extension was user set we need to
handle how we're enabling extensions in riscv_init_max_cpu_extensions().
object_property_set_bool() calls the set() callback for the property,
and we're going to use this callback to set the 'multi_ext_user_opts'
hash.

This means that, as is today, all extensions we're setting for the 'max'
CPU will be seen as user set in the future. Let's change set_bool() to
isa_ext_update_enabled() that will just enable/disable the flag on a
certain offset.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20230912132423.268494-19-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>