sama5d3-xplained:ethernet-over-phy configuration found in build testing:
arch/arm/src/sama5/sam_irq.c: Fix "Control reaches end of non-void function " warning
arch/arm/src/sama5/sam_udphs.c: Fix "unused variable 'epno'" warning
boards/arm/sama5/sama5d*-*/src/sam_usb.c: Fix "warning 'HAVE_USBHOST' not defined" warnings