ASoC: rt5640: Revise the input pin name of IN1 and IN2 in document of the devicetree

Signed-off-by: NOder Chiou <oder_chiou@realtek.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/rt5640.txt

@@ -24,9 +24,9 @@ Pins on the device (for linking into audio routes) for RT5639/RT5640:
   * DMIC2
   * MICBIAS1
   * IN1P
-  * IN1R
+  * IN1N
   * IN2P
-  * IN2R
+  * IN2N
   * HPOL
   * HPOR
   * LOUTL