MIPS: Flush TLB handlers directly after writing them

When having enabled MIPS_PGD_C0_CONTEXT, trap_init() might call the
generated tlbmiss_handler_setup_pgd before it was committed to memory,
causing boot failures:

  trap_init()
   |- per_cpu_trap_init()
   |   |- TLBMISS_HANDLER_SETUP()
   |       |- tlbmiss_handler_setup_pgd()
   |- flush_tlb_handlers()

To avoid this, move flush_tlb_handlers() into build_tlb_refill_handler()
right after they were generated. We can do this as the cache handling is
initialized just before creating the tlb handlers.

This issue was introduced in 3d8bfdd030
("MIPS: Use C0_KScratch (if present) to hold PGD pointer.").

Signed-off-by: Jonas Gorski <jogo@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Jayachandran C <jchandra@broadcom.com>
Cc: David Daney <david.daney@cavium.com>
Patchwork: https://patchwork.linux-mips.org/patch/5539/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/traps.c

@@ -1627,7 +1627,6 @@ void *set_vi_handler(int n, vi_handler_t addr)
 }
 
 extern void tlb_init(void);
-extern void flush_tlb_handlers(void);
 
 /*
  * Timer interrupt
@@ -1956,7 +1955,6 @@ void __init trap_init(void)
 		set_handler(0x080, &except_vec3_generic, 0x80);
 
 	local_flush_icache_range(ebase, ebase + 0x400);
-	flush_tlb_handlers();
 
 	sort_extable(__start___dbe_table, __stop___dbe_table);