MIPS: Use C0_KScratch (if present) to hold PGD pointer.

Decide at runtime to use either Context or KScratch to hold the PGD
pointer.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1876/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/traps.c

@@ -1592,7 +1592,6 @@ void __cpuinit per_cpu_trap_init(void)
 #endif /* CONFIG_MIPS_MT_SMTC */
 
 	cpu_data[cpu].asid_cache = ASID_FIRST_VERSION;
-	TLBMISS_HANDLER_SETUP();
 
 	atomic_inc(&init_mm.mm_count);
 	current->active_mm = &init_mm;
@@ -1614,6 +1613,7 @@ void __cpuinit per_cpu_trap_init(void)
 		write_c0_wired(0);
 	}
 #endif /* CONFIG_MIPS_MT_SMTC */
+	TLBMISS_HANDLER_SETUP();
 }
 
 /* Install CPU exception handler */