phy: Add UFS PHY modes

UFS phy has two modes for each High speed generation.
These modes are identified by two rates of operations -
Rate A, and Rate B.
Add these UFS phy modes to phy framework.

Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>