dt-bindings: memory: mediatek: update mediatek,smi-larb.yaml references

Changeset 27bb0e42 ("dt-bindings: memory: mediatek: Convert SMI to DT schema")
renamed: Documentation/devicetree/bindings/memory-controllers/mediatek,smi-larb.txt
to: Documentation/devicetree/bindings/memory-controllers/mediatek,smi-larb.yaml.

Update its cross-references accordingly.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/c70bd79b311a65babe7374eaf81974563400a943.1610535350.git.mchehab+huawei@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>