hw/char/mcf_uart: Have mcf_uart_create() return DeviceState

hw/char/mcf_uart: Have mcf_uart_create() return DeviceState

There is no point in having mcf_uart_init() demote the DeviceState
pointer and return a void one. Directly return the real typedef.

mcf_uart_init() do both init + realize: rename as mcf_uart_create().

Similarly, mcf_uart_mm_init() do init / realize / mmap: rename as
mcf_uart_create_mmap().

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20231019104929.16517-1-philmd@linaro.org>
Signed-off-by: Thomas Huth <huth@tuxfamily.org>