mmc: meson-gx: work around broken SDIO with certain WiFi chips

There have been reports about SDIO failing with certain WiFi chips in
descriptor chain mode. SD / eMMC are working fine.

So let's fall back to bounce buffer mode for command SD_IO_RW_EXTENDED.
This was reported to fix the error.

Fixes: 79ed05e3 "mmc: meson-gx: add support for descriptor chain mode"
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>