ArmVirtPkg: RMM 1.0-eac1 - Relax alignment of RSI host call arg

The RMM 1.0-eac1 relaxed the RSI_HOST_CALL alignment requirement
from 4KB to 256B.

Therefore, update the alignment check for the address parameter
of the RSI_HOST_CALL command to relax the alignment requirement
to 256 bytes.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>