hw/i3c: Fix array bounds and storage in i3c_addr_is_rsvd()

The size of the is_rsvd lookup table in i3c_addr_is_rsvd() is 255 but should be 256 to cover all possible uint8_t address values and avoid potential out-of-bounds access. The array should be static too as it's a constant lookup table. Reviewed-by: Jamin Lin <jamin_lin@aspeedtech.com> Reviewed-by: Nabih Estefan <nabihestefan@google.com> Link: https://lore.kernel.org/qemu-devel/20260302193931.382228-1-clg@redhat.com Signed-off-by: Cédric Le Goater <clg@redhat.com>