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This reverts commit 5089c4a8

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This breaks validation and enumeration of display capable modifiers.

The early return true means the rest of the validation code never gets
executed, and we need that to enumerate the right modifiers to userspace
for the format.

The modifiers that are in the initial list generated for a plane are the
superset for all formats and we need the proper checks in this function
to filter some of them out for formats with which they're invalid to be
used.

Furthermore, the safety contract here is that we validate the incoming
modifiers to ensure the kernel can handle them and the display hardware
can handle them. This includes e.g. rejecting multi-plane images with DCC.

Note that the legacy swizzle mechanism allows encoding more swizzles, and
at fb creation time we convert them to modifiers and reject those with
no corresponding modifiers. If we are seeing rejections I'm happy to
help define modifiers that correspond to those, or if absolutely needed
implement a fallback path to allow for less strict validation of the
legacy path.

However, I'd like to revert this patch, since any of these is going to
be a significant rework of the patch, and I'd rather not the regression
gets into a release or forgotten in the meantime.
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>