SPI block read fix 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.
SPI block read fix
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.

andcor02/mbed-os,andcor02/mbed-os,kjbracey-arm/mbed,mbedmicro/mbed,kjbracey-arm/mbed,andcor02/mbed-os,betzw/mbed-os,c1728p9/mbed-os,betzw/mbed-os,betzw/mbed-os,betzw/mbed-os,c1728p9/mbed-os,andcor02/mbed-os,c1728p9/mbed-os,c1728p9/mbed-os,c1728p9/mbed-os,betzw/mbed-os,c1728p9/mbed-os,andcor02/mbed-os,kjbracey-arm/mbed,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,betzw/mbed-os,mbedmicro/mbed,kjbracey-arm/mbed,mbedmicro/mbed