As pointed out by Geert Uytterhoeven, the patch was incorrect
and breaks the driver, which was fortunately pointed out by
this gcc warning:
drivers/staging/iio/adc/ad7606_spi.c: In function ‘ad7606_spi_read_block’:
drivers/staging/iio/adc/ad7606_spi.c:34: warning: ‘data’ is used uninitialized in this function
The effect of the patch is that the data is copied into
a random memory location (from the uninitialized pointer)
instead of being byteswapped in place.
This adds the initialization for the 'data' variable back
to restore the original behavior.