Add driver for ReSpeaker 2-Mics Pi HAT

Please note that to use this card has to replace(overwrite)
the original simple-audio-card, since there will be a
conflict if both exist. So I just put the referenced .dts
in driver folder.

Change-Id: I7600ab1a1a54ecb0f6c779edfec1c71885c10407
Reviewed-on: https://tp-biosrd-v02/gerrit/81526
Reviewed-by: Scorpio Chang(張志賢) <Scorpio_Chang@asus.com>
Tested-by: Scorpio Chang(張志賢) <Scorpio_Chang@asus.com>

Author: yc-hou-0919

drivers/misc/Makefile

@@ -63,3 +63,4 @@ obj-$(CONFIG_UID_SYS_STATS) += uid_sys_stats.o
 obj-$(CONFIG_MEMORY_STATE_TIME) += memory_state_time.o
 obj-$(CONFIG_USB_CAM_GPIO)	+= usb_cam_gpio.o
 obj-$(CONFIG_TINKER_MCU)        += tinker_mcu.o
+obj-y				+= voice_card/

drivers/misc/voice_card/Makefile

@@ -0,0 +1 @@
+obj-y				+= ac108.o wm8960.o

drivers/misc/voice_card/Readmd

@@ -0,0 +1,3 @@
+To use this card has to replace(overwrit) the original simple-audio-card first, since there will be a conflict if both exist.
+So I left the modified dts in the folder, you can reference to the file and add the audio card manually.
+