ARM: dts: msm: Force USB to high speed mode on QRD855

USB super speed functionality is not stable on QRD855 as
re-driver is not enabled. Hence force USB speed as high-speed
only for stable functionality.

Change-Id: Idf3fc921b18a1896654ea45a4d6fcc84d8b25d5f
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>