phy: pipe3: insert delay to enumerate in GEN2 mode

8-bit delay value (0xF1) is required for GEN2 devices to be enumerated
consistently. Added an API to be called from PHY drivers to set this delay
value and called it from PIPE3 driver to set the delay value.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Roger Quadros <rogerq@ti.com>