When the device port is in a low power state [U3/L2/Not Connected],
accesses to usb device registers may take a long time. This could lead to
potential core hang when the controller registers are accessed after the
port is disabled by setting DEVDS field. Setting the fast register access
bit ensures that the PHY clock is keeping up in active state.
Therefore, set fast access bit to ensure the accesses to device registers
are quick even in low power states.
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>