ASoC: Fix swap of left and right channels for WM8993/4 speaker boost gain

SPKOUTL_BOOST start from third bit, SPKOUTLR_BOOST start from 0 bit.

Signed-off-by: Uk Kim <w0806.kim@samsung.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@kernel.org