powerpc/44x: use patch_sites for TLB handlers patching

Use patch sites and associated helpers to manage TLB handlers
patching instead of hardcoding.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/nohash/32/mmu-44x.h

@@ -111,6 +111,9 @@ typedef struct {
 	unsigned long	vdso_base;
 } mm_context_t;
 
+/* patch sites */
+extern s32 patch__tlb_44x_hwater_D, patch__tlb_44x_hwater_I;
+
 #endif /* !__ASSEMBLY__ */
 
 #ifndef CONFIG_PPC_EARLY_DEBUG_44x