ArmPkg: MmCommunicationDxe: MM communicate function argument attributes

ArmPkg: MmCommunicationDxe: MM communicate function argument attributes

Current MM communicate2 function from ArmPkg described input arguments
`CommBufferPhysical`, `CommBufferVirtual` and `CommSize` as input only,
which mismatches with the "input and output type" as in PI specification.

This change updated function descriptions of MM communite2 to match input
argument types.

Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Kun Qin <kuqin12@gmail.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>