usb: phy: samsung: fix sparse warning

Fix the following sparse warning:

drivers/usb/phy/phy-samsung-usb2.c:50:26: sparse: incorrect type in argument 1 (different address spaces)
drivers/usb/phy/phy-samsung-usb2.c:50:26:    expected void const volatile [noderef] <asn:2>*addr
drivers/usb/phy/phy-samsung-usb2.c:50:26:    got void *

Cc: Vivek Gautam <gautam.vivek@samsung.com>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>