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/include/asm/mmu_context.h

@@ -29,13 +29,7 @@
 #define TLBMISS_HANDLER_SETUP_PGD(pgd)				\
 	tlbmiss_handler_setup_pgd((unsigned long)(pgd))
 
-static inline void tlbmiss_handler_setup_pgd(unsigned long pgd)
-{
-	/* Check for swapper_pg_dir and convert to physical address. */
-	if ((pgd & CKSEG3) == CKSEG0)
-		pgd = CPHYSADDR(pgd);
-	write_c0_context(pgd << 11);
-}
+extern void tlbmiss_handler_setup_pgd(unsigned long pgd);
 
 #define TLBMISS_HANDLER_SETUP()						\
 	do {								\