ARM: dts: stm32: add LTDC support for STM32MP13x SoC family

STM32MP13x SoC family embeds a new version of LTDC (Liquid crystal
display - Thin film transistor) Display Controller.

It provides a parallel digital RGB (red, green, blue) and signals for
horizontal, vertical synchronization, pixel clock and data enable as
output to interface directly to a variety of LCD-TFT panels.

Main features
  * 2 input layers blended together to compose the display
  * Cropping of layers from any input size and location
  * Multiple input pixel formats:
    – Predefined ARGB, with 7 formats: ARGB8888, ABGR8888, RGBA8888,
    BGRA8888, RGB565, BGR565, RGB888packed.
    – Flexible ARGB, allowing any width and location for A,R,G,B
    components.
    – Predefined YUV, with 3 formats: YUV422-1L (FourCC: YUYV,
    Interleaved), YUV420-2L (FourCC: NV12, semi planar), YUV420-3L
    (FourCC: Yxx, full planar) with some flexibility on the sequence of
    the component.
  * Color look-up table (CLUT) up to 256 colors (256x24 bits) per layer
  * Color transparency keying
  * Composition with flexible window position and size versus output
  display
  * Blending with flexible layer order and alpha value (per pixel or
  constant)
  * Background underlying color
  * Gamma with non-linear configurable table
  * Dithering for output with less bits per component (pseudo-random on
  2 bits)
  * Polarity inversion for HSync, VSync, and DataEnable outputs
  * Output as RGB888 24 bpp or YUV422 16 bpp
  * Secure layer (using Layer2) capability, with grouped regs and
  additional interrupt set
  * Interrupts based on 7 different events
  * AXI master interface with long efficient bursts (64 or 128 bytes)

Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Signed-off-by: Yannick Fertre <yannick.fertre@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm/boot/dts/st/stm32mp135.dtsi

@@ -19,5 +19,16 @@
 			port {
 			};
 		};
+
+		ltdc: display-controller@5a001000 {
+			compatible = "st,stm32-ltdc";
+			reg = <0x5a001000 0x400>;
+			interrupts = <GIC_SPI 88 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 89 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&rcc LTDC_PX>;
+			clock-names = "lcd";
+			resets = <&scmi_reset RST_SCMI_LTDC>;
+			status = "disabled";
+		};
 	};
 };