Using fix from mbed-os core, where few devices were failing with
SPI block read, as default data on SPI was sent 0x00.
Using API 'set_default_write_value' to set the default tx fill data.
CMD9 fails for few cards if spi.write is performed during deslect of card
Card immediately sends start packet token, which goes missing in this dummy
write to SPI. Should not clock SPI bus in deselect operation.