phy: Fix armada375 compile test build on UM

The phy-armada375-usb2 driver uses IOMEM functions so COMPILE_TEST && OF
build failed with:

drivers/built-in.o: In function `armada375_usb_phy_probe':
phy-armada375-usb2.c:(.text+0x121d): undefined reference to
`devm_ioremap_resource'
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/Kconfig

@@ -32,7 +32,7 @@ config PHY_BERLIN_SATA
 config ARMADA375_USBCLUSTER_PHY
 	def_bool y
 	depends on MACH_ARMADA_375 || COMPILE_TEST
-	depends on OF
+	depends on OF && HAS_IOMEM
 	select GENERIC_PHY
 
 config PHY_DM816X_USB