ARM: dts: qcom: msm8960: Add USB node

Add the required nodes to support USB on the MSM8960 SoC. As it's very
similar to the APQ8064 SoC, the nodes are almost identical

Add a label to sleep_clk for the USB node to reference

Signed-off-by: Rudraksha Gupta <guptarud@gmail.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230607050025.86636-4-guptarud@gmail.com