Use MaxPacketSize as the initial buffer size to read data.

Use MaxPacketSize as the initial buffer size to read data.

If host sends more than 8 bytes of data, BABBLE error would happen if USB3 debug library uses 8 byte of buffer to read data.
We need use MaxPacketSize in USB3 debug descriptor to create buffer and read data into this buffer.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Elvin Li <elvin.li@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16762 6f19259b-4bc3-4df7-8a09-765794883524