USB: Add platform device support for the ISP1760 USB chip

USB: Add platform device support for the ISP1760 USB chip

Currently, the driver only supports PCI and PPC_OF but there are
boards like ARM RealView where this is a platform device. The patch adds
the necessary functions and registration to the isp1760-if.c file and
modifies the corresponding Makefile and Kconfig to be able to use this
driver even if PCI and PPC_OF are not enabled.

Signed-off-by: Catalin Marinas <[email protected]>
Cc: Sebastian Siewior <[email protected]>
Cc: Russell King <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>