rddaniel: pl011: mark power domain identifier as none

Commit ef5071cb ("pl011: Add powerup/powerdown handlers") introduced a
configurable power domain identifier that the driver can be informed of
power state changes. For RD-Daniel platform, mark this domain identifier
as none as these notifications can be ignored for now.

Change-Id: Ic10d77f1ef89b317fe1851290e13af9639b0ec50
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>