Hisilicon/D06: Use HCCS speed with 2.6G
Follow chip team suggestion, HCCS(Huawei Cache-Coherent System)
may be unstable while speed is 3.0G, so use 2.6G to avoid some
unstable stress issue.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ming Huang <ming.huang@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>