mmc: disable SPI CRC

CRC errors on SPI bus usually means there is something wrong with the
hardware(unstable voltage, wiring, etc).

Disable SPI CRC in favor of improving performance as the cost of
detecting hardware errors are too high, and not all that useful.

Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
Change-Id: I5d7ef9dedbddf8d7f4c4911788051a7753eb67d8

drivers/mmc/core/core.c

@@ -77,7 +77,7 @@ static const unsigned freqs[] = { 400000, 300000, 200000, 100000 };
  * performance cost, and for other reasons may not always be desired.
  * So we allow it it to be disabled.
  */
-bool use_spi_crc = 1;
+bool use_spi_crc = 0;
 module_param(use_spi_crc, bool, 0);
 
 static int mmc_schedule_delayed_work(struct delayed_work *work,