ARM: dts: armada-370-db: Fix stereo audio input routing on Armada 370

The simple-audio-card configuration for the Armada 370 development
board incorrectly routed the left channel signal ("AIN1L") to both
sides of the stereo "In Jack".

This commit corrects the typo for the right channel, changing the
second "AIN1L" entry to "AIN1R" to enable proper stereo input
recording.

Signed-off-by: Jihed Chaibi <jihed.chaibi.dev@gmail.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>