dt-bindings: arm: qcom: Document APQ8026 SoC binding

Document the APQ8026 (based on MSM8226) SoC device-tree binding and the
LG G Watch R.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210911232707.259615-8-luca@z3ntu.xyz