phy: cadence: Sierra: Check PIPE mode PHY status to be ready for operation

PIPE phy status is used to communicate the completion of several PHY
functions. Check if PHY is ready for operation while configured for
PIPE mode during startup.

Signed-off-by: Swapnil Jakhade <sjakhade@cadence.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>