Explicitly use libusb1.0 headers

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
Merge branch 'master' of git://github.com/boundarydevices/imx_usb_loader
imx_usb: remove use of current working directory

Updated to expect to find .conf file in the same location
as the imx_usb binary, primarily so we can run this in
the U-Boot build directory:
	~/u-boot-imx6$ make all && ~/imx_usb_loader/imx_usb u-boot.imx

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>