ath79: add support for D-Link DIR-842 C3

Hardware spec of DIR-842 C3:
SoC: QCA9563
DRAM: 128MB DDR2
Flash: 16MB SPI-NOR
Switch: QCA8337N
WiFi 5.8GHz: QCA9888
WiFi 2.4Ghz: QCA9563
USB: circuit onboard, but components are not soldered

Flash instructions:

1. Upgrade the factory.bin through the factory web interface or
   the u-boot failsafe interface.
   The firmware will boot up correctly for the first time.
   Do not power off the device after OpenWrt has booted.
   Otherwise the u-boot will enter failsafe mode as the checksum
   of the firmware has been changed.
2. Upgrade the sysupgrade.bin in OpenWrt.
   After upgrading completes the u-boot won't complain about the
   firmware checksum and it's OK to use now.
3. If you powered off the device before upgrading the sysupgrade.bin,
   just upgrade the factory.bin through the u-boot failsafe interface
   and then goto step 2.

Signed-off-by: Perry Melange <isprotejesvalkata@gmail.com>

target/linux/ath79/base-files/etc/hotplug.d/firmware/10-ath9k-eeprom

@@ -107,6 +107,7 @@ case "$FIRMWARE" in
 		;;
 	dlink,dir-842-c1|\
 	dlink,dir-842-c2|\
+        dlink,dir-842-c3|\
 	dlink,dir-859-a1|\
 	nec,wg1200cr|\
 	wd,mynet-n750)

target/linux/ath79/base-files/etc/hotplug.d/firmware/11-ath10k-caldata

@@ -191,6 +191,7 @@ case "$FIRMWARE" in
 	case $board in
 	dlink,dir-842-c1|\
 	dlink,dir-842-c2|\
+        dlink,dir-842-c3|\
 	nec,wg1200cr)
 		ath10kcal_extract "art" 20480 12064
 		ath10kcal_patch_mac_crc $(mtd_get_mac_ascii devdata wlan5mac)