arm64: mm: cleanup stale AIVIVT references

Since commit:

  155433cb365ee466 ("arm64: cache: Remove support for ASID-tagged VIVT I-caches")

... the kernel no longer cares about AIVIVT I-caches, as these were
removed from the architecture.

This patch removes the stale references to such I-caches.

The comment in flush_context() is also updated to clarify when and where
the TLB invalidation occurs.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/cacheflush.h

@@ -38,7 +38,7 @@
  *
  *	See Documentation/cachetlb.txt for more information. Please note that
  *	the implementation assumes non-aliasing VIPT D-cache and (aliasing)
- *	VIPT or ASID-tagged VIVT I-cache.
+ *	VIPT I-cache.
  *
  *	flush_cache_mm(mm)
  *

arch/arm64/mm/context.c

@@ -117,7 +117,10 @@ static void flush_context(unsigned int cpu)
 		per_cpu(reserved_asids, i) = asid;
 	}
 
-	/* Queue a TLB invalidate and flush the I-cache if necessary. */
+	/*
+	 * Queue a TLB invalidation for each CPU to perform on next
+	 * context-switch
+	 */
 	cpumask_setall(&tlb_flush_pending);
 }