accel/ivpu: Fix missing MMU events if file_priv is unbound

Move the ivpu_mmu_discard_events() function to the common portion of
the abort work function. This ensures it is called only once, even if
there are no faulty contexts in context_xa, to guarantee that MMU events
are discarded and new events are not missed.

Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Signed-off-by: Karol Wachowski <karol.wachowski@intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129125636.1047413-4-jacek.lawrynowicz@linux.intel.com