hw/riscv/numa.c: use g_autofree in socket_fdt_write_distance_matrix()

hw/riscv/numa.c: use g_autofree in socket_fdt_write_distance_matrix()

Use g_autofree in 'dist_matrix' to avoid the manual g_free().

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240122221529.86562-3-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>