[PATCH v2 2/3] ACPI: arm64: Add support for the FF-A FFH Operation Region (offset 2)

[Jamie Nguyen]

> There is a acpi_ffh_ffa_length_valid() check in acpi_ffh_ffa_handler(),
> is it a duplicated one here?

A failed acpi_ffh_ffa_length_valid() check is reported through X0.
However, a region shorter than 64 bits has no X0 field in which to return
that status, so this path returns AE_ERROR instead.

I'll add a comment explaining that distinction in v3.