scsi: ufs: UFS device spec version for G4 and low voltage support

UFS HS-G4 and low voltage support features are supported in UFS
device specification version 3.0. To enable these features, driver
is not just checking the specification version but it also reads
the HS-G4 capability. Checking HS-G4 capability is not required so
this change removes the check.

Change-Id: I1e712aeabaa63fb742809a8f9c2dced94a71f5a8
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>