core: Kill the 'host_endian' argument for most functions

core: Kill the 'host_endian' argument for most functions

The 'host_endian' argument exists only for a special case in the Linux
backend, that being when the device descriptor is read using usbfs
rather than sysfs. It does not apply to any other descriptor types nor
any other backends, so remove it.

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>