dts: bindings: Remove unused 'version' field

No binding has anything but 'version: 0.1', and the code in scripts/dts/
never does anything with it except print a warning if it isn't there.
It's undocumented what it means.

I suspect it's overkill if it's meant to be the binding format version.
If we'd need to tell different versions from each other, we could change
some other minor thing in the format, and it probably won't be needed.

Remove the 'version' fields from the bindings and the warning from the
scripts/dts/ scripts.

The new device tree script will give an error when unknown fields appear
in bindings.

The deletion was done with

    git ls-files 'dts/bindings/*.yaml' | xargs sed -i '/^\s*version: /d'

Some blank lines at the beginning of bindings were removed as well.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>

dts/bindings/riscv/openisa,rv32m1-pcc.yaml

@@ -5,7 +5,6 @@
 #
 
 title: RV32M1 PCC (Peripheral Clock Control)
-version: 0.1
 
 description: >
     This is a representation of the RV32M1 PCC IP node