dt-bindings: mediatek: add bindings for MediaTek MT7622 SoC

This adds dt-binding documentation for MediaTek MT7622 SoC
which currently only includes basic items such as ARM CPU,
MediaTek SYSIRQ and UART.
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

Documentation/devicetree/bindings/arm/mediatek.txt

@@ -13,6 +13,7 @@ compatible: Must contain one of
    "mediatek,mt6755"
    "mediatek,mt6795"
    "mediatek,mt6797"
+   "mediatek,mt7622"
    "mediatek,mt7623"
    "mediatek,mt8127"
    "mediatek,mt8135"
@@ -42,6 +43,9 @@ Supported boards:
 - Evaluation board for MT6797(Helio X20):
     Required root node properties:
       - compatible = "mediatek,mt6797-evb", "mediatek,mt6797";
+- Reference board variant 1 for MT7622:
+    Required root node properties:
+      - compatible = "mediatek,mt7622-rfb1", "mediatek,mt7622";
 - Evaluation board for MT7623:
     Required root node properties:
       - compatible = "mediatek,mt7623-evb", "mediatek,mt7623";

Documentation/devicetree/bindings/interrupt-controller/mediatek,sysirq.txt

-+Mediatek 65xx/67xx/81xx sysirq
++Mediatek MT65xx/MT67xx/MT81xx sysirq
 
 Mediatek SOCs sysirq support controllable irq inverter for each GIC SPI
 interrupt.
@@ -8,6 +8,7 @@ Required properties:
 	"mediatek,mt8173-sysirq", "mediatek,mt6577-sysirq": for MT8173
 	"mediatek,mt8135-sysirq", "mediatek,mt6577-sysirq": for MT8135
 	"mediatek,mt8127-sysirq", "mediatek,mt6577-sysirq": for MT8127
+	"mediatek,mt7622-sysirq", "mediatek,mt6577-sysirq": for MT7622
 	"mediatek,mt6795-sysirq", "mediatek,mt6577-sysirq": for MT6795
 	"mediatek,mt6797-sysirq", "mediatek,mt6577-sysirq": for MT6797
 	"mediatek,mt6755-sysirq", "mediatek,mt6577-sysirq": for MT6755

Documentation/devicetree/bindings/serial/mtk-uart.txt

@@ -9,6 +9,7 @@ Required properties:
   * "mediatek,mt6755-uart" for MT6755 compatible UARTS
   * "mediatek,mt6795-uart" for MT6795 compatible UARTS
   * "mediatek,mt6797-uart" for MT6797 compatible UARTS
+  * "mediatek,mt7622-uart" for MT7622 compatible UARTS
   * "mediatek,mt7623-uart" for MT7623 compatible UARTS
   * "mediatek,mt8127-uart" for MT8127 compatible UARTS
   * "mediatek,mt8135-uart" for MT8135 compatible UARTS