ArmVirtPkg: RMM 1.0-eac5 - Attestation token API updates

The RMM 1.0-eac3 specification removed the restriction that
attestation token size must not exceed 4KB. Further it also
extended the RSI_ATTESTATION_TOKEN_CONTINUE command so as to
return up to a granule worth of the attestation token data.

The RMM 1.0-eac5 specification simplified the attestation
token interfaces such that, the RSI_ATTESTATION_TOKEN_INIT
command returns the upper bound of the attestation token
size. This eliminates the need for relocation of token data
buffers during attestation token retrieval.

Therefore, implement the attestation token API updates
from RMM 1.0-eac3 through to RMM 1.0-eac5 specification.

Note: The RsiGetAttestationToken() API has been modified
such that ArmCcaRsiLib allocates memory for the returned
attestation token buffer. The caller is therefore required
to call RsiFreeAttestationToken() to free the memory that
was allocated for the attestation token buffer.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>