spi: loopback: match configuration of test to description

The test "two tx+rx transfers - alter second" actually modifies
the first not the second transfer, which - in conjunction with
testing the read data - results also in overwriting data read
earlier.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
1 file changed