usb.c: change a cast that was causing a problem on MSVC.
usb.c: change a cast that was causing a problem on MSVC.

I guess doing a '(long) UINT_MAX' was causing a problem with MSVC, so
remove that.

A usb 'bus' can only be uint8_t, so if it is larger than that - fail.

Signed-off-by: Robin Getz <c66e5a86ef9317cf35cecb2ed063996b2100ed4b@analog.com>

analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio