drm/tidss: implement WA for AM65xx erratum i2000

drm/tidss: implement WA for AM65xx erratum i2000

This patch implements WA for AM65xx erratum i2000, which causes YUV
formats to show wrong colors.

An earlier patch removed a partial WA:

a568800b6c422eda898d94c9d68355915e438a73 ("drm/tidss: remove AM65x PG1 YUV erratum code")

The patch explains the reasoning for removal. The change in plans has
been that it has become clear that there are and will be users for PG1
SoCs and as such it's good to implement the WA for PG1s.

This patch adds the WA back so that it is only used on SR1.0 (which is
the new name for PG1). The previous WA code didn't check the SoC
revision, which this patch does.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200812112625.59897-1-tomi.valkeinen@ti.com
Reviewed-by: Jyri Sarha <jsarha@ti.com>