ipq40xx: tidy up dts-v1 statements

ipq40xx: tidy up dts-v1 statements

The "/dts-v1/;" identifier is supposed to be present once at the
top of a device tree file after the includes have been processed.

Therefore, adding it to a DTS _and_ a DTSI file is actually wrong,
as it will be present twice then (though the compiler does not
complain about it).

In ipq40xx, the dts-v1 statement is already included in
qcom-ipq4019.dtsi, so we don't have to add it anywhere at all.
However, based on the conditions stated above, this requires
qcom-ipq4019.dtsi to be included as the first file in any DTS(I).

Consequently, this patch removes all cases of dts-v1 for the
ipq40xx target, and moves the includes accordingly where necessary.

While at it, remove a few obviously unneeded includes on the way.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>