Avoid declaring PXA2xxMMCIState local variable, return it directly.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Acked-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20200705213350.24725-3-f4bug@amsat.org>