dt-bindings: display: mediatek: dpi: Revise mediatek strings to correct format

Strings replacement:
- s/mediatek/MediaTek/ in title.
- s/Mediatek/MediaTek/ in description.
Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20220701035845.16458-3-rex-bc.chen@mediatek.com/Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

Documentation/devicetree/bindings/display/mediatek/mediatek,dpi.yaml

@@ -4,14 +4,14 @@
 $id: http://devicetree.org/schemas/display/mediatek/mediatek,dpi.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: mediatek DPI and DP_INTF Controller
+title: MediaTek DPI and DP_INTF Controller
 
 maintainers:
   - CK Hu <ck.hu@mediatek.com>
   - Jitao shi <jitao.shi@mediatek.com>
 
 description: |
-  The Mediatek DPI and DP_INTF function blocks are a sink of the display
+  The MediaTek DPI and DP_INTF function blocks are a sink of the display
   subsystem and provides 8-bit RGB/YUV444 or 8/10/10-bit YUV422 pixel data on a
   parallel output bus.