[POWERPC] Reworking machine check handling and Fix 440/440A

This adds a cputable function pointer for the CPU-side machine
check handling. The semantic is still the same as the old one,
the one in ppc_md. overrides the one in cputable, though
ultimately we'll want to change that so the CPU gets first.

This removes CONFIG_440A which was a problem for multiplatform
kernels and instead fixes up the IVOR at runtime from a setup_cpu
function. The "A" version of the machine check also tweaks the
regs->trap value to differenciate the 2 versions at the C level.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

arch/powerpc/kernel/cpu_setup_44x.S

@@ -23,11 +23,20 @@ _GLOBAL(__setup_cpu_440epx)
 	mflr	r4
 	bl	__init_fpu_44x
 	bl	__plb_disable_wrp
+	bl	__fixup_440A_mcheck
 	mtlr	r4
 	blr
 _GLOBAL(__setup_cpu_440grx)
 	b	__plb_disable_wrp
+_GLOBAL(__setup_cpu_440gx)
+_GLOBAL(__setup_cpu_440spe)
+	b	__fixup_440A_mcheck
 
+ /* Temporary fixup for arch/ppc until we kill the whole thing */
+#ifndef CONFIG_PPC_MERGE
+_GLOBAL(__fixup_440A_mcheck)
+	blr
+#endif
 
 /* enable APU between CPU and FPU */
 _GLOBAL(__init_fpu_44x)