scsi: ufs: update SVS mode enter/exit sequence for UFS controller V4.x.x

UFS host controller V4.0.0 onwards requires mandatory writing to
UFS_SYS1CLK_1US.SYS1CLK_1US_REG register bits in SVS mode enter/exit
sequence. And PA_VS_CORE_CLK_40NS_CYCLES attribute is newly added to be set
per programmed frequency of unipro core clock of UFS host controller in SVS
mode enter/exit sequence.

Change-Id: If823c836616747d0a3c1dac32dc5f4e359acd634
Signed-off-by: Can Guo <cang@codeaurora.org>