drm: mali-dp: fix stride setting for multi-plane formats

Hardware has multiple (2 or 3, depending on model) stride
registers per layer; add a function that correctly takes that
into account. On hardware that only has 2 stride registers,
ensure that 3-plane (YUV) content has identical strides
for both chroma planes.

Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com>
[Removed smart layer stride setup, comment and commit message clarifications]
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

drivers/gpu/drm/arm/malidp_hw.h

@@ -58,6 +58,7 @@ struct malidp_layer {
 	u16 id;			/* layer ID */
 	u16 base;		/* address offset for the register bank */
 	u16 ptr;		/* address offset for the pointer register */
+	u16 stride_offset;	/* Offset to the first stride register. */
 };
 
 /* regmap features */
@@ -93,6 +94,10 @@ struct malidp_hw_regmap {
 	const u8 bus_align_bytes;
 };
 
+/* device features */
+/* Unlike DP550/650, DP500 has 3 stride registers in its video layer. */
+#define MALIDP_DEVICE_LV_HAS_3_STRIDES	BIT(0)
+
 struct malidp_hw_device {
 	const struct malidp_hw_regmap map;
 	void __iomem *regs;