Qemu pipe access with parameter

In current implementation, each qemu_pipe read/write buffer requires severals
MMIO operations to pass down the parameters like buffer address, pipe, length
etc. This has impacts on emulator performance when running under the HAXM
environment because each MMIO access cause expensive transition from guest to
HAXM driver and QEMU process.
To reduce the overhead, we put the parameter into a buffer without causing
MMIO access, and then invoke a single MMIO operation needed for the access
command.

Change-Id: I1bce409a76ed69b2f9e91d86265a61c81493e9f8
Signed-off-by: Xin, Xiaohui <xiaohui.xin@intel.com>
Signed-off-by: Jiang, Yunhong <yunhong.jiang@intel.com>
Signed-off-by: Nakajima, Jun <jun.nakajima@intel.com>