hw/sd/pxa2xx_mmci: add read/write() trace events

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Message-id: 20180104000156.30932-1-f4bug@amsat.org
[PMM: add missing include]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>