phy: miphy28lp: Pass sysconfig register offsets via syscfg dt property.

Based on Arnds review comments here https://lkml.org/lkml/2014/11/13/161,
update the miphy28lp phy driver to access sysconfig register offsets via
syscfg dt property.

This is because the reg property should not be mixing address spaces like
it does currently for miphy28lp. This change then also aligns us to how other
platforms such as keystone and bcm7445 pass there syscon offsets via DT.

I have updated the miphy28lp phy driver same way as Peter's implementation.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

phy: miphy28lp: Tune tx impedance across Soc cuts

This patch to compensate tx impedance (Sata, PCIe)
depending on Soc cuts the kernel is built for.

Signed-off-by: Giuseppe Condorelli <giuseppe.condorelli@st.com>
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

phy: miphy28lp: Add SSC support for SATA

This patch to tune on/off the ssc on miphy sata setup.
User can now enable ssc via dt blob, it is useful to reduce
effects of EMI.

Signed-off-by: Giuseppe Condorelli <giuseppe.condorelli@st.com>
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

phy: miphy28lp: Add Device Tree bindings for the MiPHY28lp

The MiPHY28lp is a Generic PHY which can serve various SATA or PCIe
or USB3 devices.

Signed-off-by: alexandre torgue <alexandre.torgue@st.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>