Add short documentation-alike note on how to use the Altera SPI
driver with the EPCS/EPCQx1 FPGA IP block on SoCFPGA Cyclone V
into doc/SPI/README.altera_spi
Signed-off-by: Marek Vasut
Cc: Chin Liang See
Cc: Dinh Nguyen
Cc: Albert Aribaud
Cc: Pavel Machek
Cc: Jagannadha Sutradharudu Teki
Acked-by: Pavel Machek
Reviewed-by: Jagannadha Sutradharudu Teki