ufs: ufs-qcom: Clean up UFS PHY mode and submode selection

In hba power up sequence, phy_set_mode_ext() is used to pass UFS PHY mode
and HS gear as the submode to UFS PHY driver. UFS PHY mode is decided by
limit_rate, which is Rate-B by default. While, UFS PHY submode is dediced
by limit_phy_submode, 1 stands for G4, 0 stands for non-G4.

Change-Id: I54fc377abd42290e76094125b446d24ef1478124
Signed-off-by: Can Guo <cang@codeaurora.org>