[aacraid] Handle both AIF and SYNC interrupts

[luporl]

Summary

Without this change, if an AIF interrupt comes at the same time a SYNC command is finished, the SYNC interrupt will be lost.
This happens because all interrupt bits (bellbits) are cleared, but only one of them is handled.

Debugging shows that, (at least) when !sc->msi_enabled and (sc->flags & AAC_FLAGS_SYNC_MODE) is true (sync mode), both bits may be set at the same time.

[luporl]

sys/dev/aacraid/aacraid.c

930–931 ↗

(On Diff #68903)

This is needed to avoid entering the if block below, that uses structure fields that are not initialized (and probably not needed) in sync mode.