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 <catalin.marinas@arm.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
index b2ceb4a..89299a5 100644
--- a/drivers/usb/Makefile
+++ b/drivers/usb/Makefile
@@ -19,6 +19,7 @@
 obj-$(CONFIG_USB_U132_HCD)	+= host/
 obj-$(CONFIG_USB_R8A66597_HCD)	+= host/
 obj-$(CONFIG_USB_HWA_HCD)	+= host/
+obj-$(CONFIG_USB_ISP1760_HCD)	+= host/
 
 obj-$(CONFIG_USB_C67X00_HCD)	+= c67x00/