hw/arm/smmuv3: Fix encoding of CLASS in events

hw/arm/smmuv3: Fix encoding of CLASS in events

The SMMUv3 spec (ARM IHI 0070 F.b - 7.3 Event records) defines the
class of events faults as:

CLASS: The class of the operation that caused the fault:
- 0b00: CD, CD fetch.
- 0b01: TTD, Stage 1 translation table fetch.
- 0b10: IN, Input address

However, this value was not set and left as 0 which means CD and not
IN (0b10).

Another problem was that stage-2 class is considered IN not TT for
EABT, according to the spec:
    Translation of an IPA after successful stage 1 translation (or,
    in stage 2-only configuration, an input IPA)
    - S2 == 1 (stage 2), CLASS == IN (Input to stage)

This would change soon when nested translations are supported.

While at it, add an enum for class as it would be used for nesting.
However, at the moment stage-1 and stage-2 use the same class values,
except for EABT.

Fixes: 9bde7f0674 “hw/arm/smmuv3: Implement translate callback”
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-id: 20240715084519.1189624-4-smostafa@google.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>