Remove fallback when requesting a single USB interface.

This reverts commit 2d475d0ed37bf8f19385537ad31e361f1b21624b. The
permission broker now supports opening devices that are partially
claimed through the OpenPath method and RequestPathAccess will always
fail for these devices so the fallback path from RequestPathAccess to
OpenPath is always taken.

BUG=500057

Review URL: https://codereview.chromium.org/1227313003

Cr-Commit-Position: refs/heads/master@{#338354}
UsbControlTransferFunction::UsbControlTransferFunction() {
}

UsbControlTransferFunction::UsbControlTransferFunction() {
}
