sdcard: Allow commands valid in SPI mode

sdcard: Allow commands valid in SPI mode

From the "Physical Layer Simplified Specification Version 1.10"
  Chapter 7.3 "SPI Mode Transaction Packets"
    Table 57: "Commands and arguments"

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20180607180641.874-3-f4bug@amsat.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>