hw/i386/pc: Inline pc_cmos_init() into pc_cmos_init_late() and remove it

hw/i386/pc: Inline pc_cmos_init() into pc_cmos_init_late() and remove it

Now that pc_cmos_init() doesn't populate the X86MachineState::rtc attribute any
longer, its duties can be merged into pc_cmos_init_late() which is called within
machine_done notifier. This frees pc_piix and pc_q35 from explicit CMOS
initialization.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-Id: <20240303185332.1408-5-shentey@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>