usb: phy: initialize the notifier when add a new phy

We need to initialize the notifier before use it.

So lets initialize it when add a new phy device to
reduce the code redundancy.

Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Git-commit: 31e322272d9d7da0724ae6e3180478575aa48909
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[mgautam@codeaurora.org: fixed conflict in drivers/usb/phy/phy-generic.c]
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>
Change-Id: I400be895c3ff0f5b056f18716d5028cb54449aed