MdePkg: Update Usb2Hc Isochronous related functions' description

IsochronousTransfer/AsyncIsochronousTransfer() interface
descriptions get updated to follow UEFI2.5 spec.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Feng Tian <feng.tian@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17384 6f19259b-4bc3-4df7-8a09-765794883524
1 file changed