ARM: dts: imx6qdl-wandboard: Fix audio channel swap

[ Upstream commit 79935915300c5eb88a0e94fa9148a7505c14a02a ]

When running a stress playback/stop loop test on a mx6wandboard channel
swaps can be noticed randomly.

Increasing the SGTL5000 LRCLK pad strength to its maximum value fixes
the issue, so add the 'lrclk-strength' property to avoid the audio
channel swaps.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>