phy: bcm-ns-usb2: support updated DT binding with PHY reg space

Updated DT binding maps just a PHY's register space instead of the whole
DMU block. Accessing a common CRU reg is handled using syscon &
regmap.

The old binding has been deprecated and remains supported as a fallback
method.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20211026093716.5567-1-zajec5@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>