phy: brcm-sata: Implement 7216 initialization sequence

7216 is a 16nm process chip with a slightly different version of the PHY
SerdDeS/AFE that requires a specific tuning sequence. Key on the
compatible string to perform that initialization.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>