dt-bindings: ath10k: Add new dt entries to identify coex support

This adds new dt entries qcom,coexist-support and qcom,coexist-gpio-pin
which will be used by ath10k driver to identify coex support
of a hardware and notify wifi firmware the gpio pin number.
This pin number information is needed for the hardware QCA4019.

Signed-off-by: Tamizh Chelvam <tamizhr@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>