phy: omap-usb2-phy: Fix warnings when built for ARM64

phy: omap-usb2-phy: Fix warnings when built for ARM64

Below warning is seen when this driver is built for devices with 64 bit
physical address space.

drivers/phy/omap-usb2-phy.c: In function ‘omap_usb2_phy_probe’:
drivers/phy/omap-usb2-phy.c:187:20: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   priv->phy_base = (void *)base;
                    ^
Fix this by using dev_read_addr_ptr() instead of dev_read_addr().

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>