subsys: usb: check for invalid descriptor type request

Implementation of Get Descriptor Request should not return interface
or endpoint descriptors in a single request without configuration
descriptor, see USB Spec. Revision 2.0, 9.4.3 Get Descriptor

This patch fixes linux kernel usbtest subtest 7 and subtest 11 errors.

Signed-off-by: Johann Fischer <j.fischer@phytec.de>