Sync patch r14760 from main trunk.
Just like EhciDxe, do not reset host controller when debug capability is enabled in XhciDxe driver.

git-svn-id: svn://svn.code.sf.net/p/edk2/code/branches/UDK2010.SR1/MdeModulePkg@14762 6f19259b-4bc3-4df7-8a09-765794883524