mm: Remove tlb_flush_reason::NR_TLB_FLUSH_REASONS from <linux/mm_types.h>

This has been unused since it was added 11 years ago in:

  d17d8f9 ("x86/mm: Add tracepoints for TLB flushes")

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Link: https://patch.msgid.link/20251212-tlb-trace-fix-v2-2-d322e0ad9b69@columbia.edu

Author: tzussman

include/linux/mm_types.h

@@ -1631,7 +1631,6 @@ enum tlb_flush_reason {
 	TLB_LOCAL_MM_SHOOTDOWN,
 	TLB_REMOTE_SEND_IPI,
 	TLB_REMOTE_WRONG_CPU,
-	NR_TLB_FLUSH_REASONS,
 };
 
 /**