Revert "ANDROID: usb: host: export additional xhci symbols for ring management"

This reverts commit 6c997d15.

The symbols exported by it were never used by any external modules, so
remove the unneeded exports.

Bug: 203756332
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I338313c0c2ad1ec83f452db910a6ef9b5ee32b7d