dt-bindings: net: wireless: mt76: Fix 8-bit property sizes

The '/bits/ 8' notation applies the next <> list of values. Another <> list
is encoded as 32-bits by default. IOW, each <> list needs to be preceeded
with '/bits/ 8'.

While the dts format allows this, as a rule we don't mix sizes for DT
properties since all size information is lost in the dtb file.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220107030419.2380198-1-robh@kernel.org