riscv: mm: Fix code comment

Fix the comment since vmalloc_fault doesn't reach
flush_tlb_fix_spurious_fault.

Signed-off-by: ShihPo Hung <shihpo.hung@sifive.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: linux-riscv@lists.infradead.org
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/mm/fault.c

@@ -272,9 +272,6 @@ vmalloc_fault:
 		 * entries, but in RISC-V, SFENCE.VMA specifies an
 		 * ordering constraint, not a cache flush; it is
 		 * necessary even after writing invalid entries.
-		 * Relying on flush_tlb_fix_spurious_fault would
-		 * suffice, but the extra traps reduce
-		 * performance. So, eagerly SFENCE.VMA.
 		 */
 		local_flush_tlb_page(addr);