Revert "Use SPI.transfer for spiRec where applicable"

[sandeepmistry]

This reverts commit 2f6748f as suggested by @greiman.

Which should fix arduino/Arduino#5805 and arduino/Arduino#5792.

I did a 10 MB read performance test with the following sketch:

#include <SPI.h>
#include <SD.h>

File myFile;

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(115200);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


  Serial.print("Initializing SD card...");

  if (!SD.begin(4)) {
    Serial.println("initialization failed!");
    return;
  }
  Serial.println("initialization done.");

  myFile = SD.open("USS.WAV");

  if (!myFile) {
    // if the file didn't open, print an error:
    Serial.println("error opening file");
    while (1);
  }


  unsigned long start = micros();

  for (int i = 0; i < ((10 * 1024 * 1024) / 512); i++) {
    byte data[512];
    myFile.read(data, sizeof(data));
  }

  unsigned long end = micros();

  Serial.println(end - start);

  myFile.close();
}

void loop() {
}

Results are as follows:

• v1.0.9: 41594020 microseconds
• v1.1.0: 41593834 microseconds
• v1.1.0 + memset of 0xff in spiRec: 41594502 microseconds

so I think the best option is to revert the commit.

cc/ @Fede85 @cmaglie @akash73