Avoid using a magic number (4) everywhere for the number of chip
selects supported.
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-id: 20210129132323.30946-2-bmeng.cn@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>