[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>
diff --git a/include/asm-powerpc/ptrace.h b/include/asm-powerpc/ptrace.h
index 13fccc5..c662287 100644
--- a/include/asm-powerpc/ptrace.h
+++ b/include/asm-powerpc/ptrace.h
@@ -106,7 +106,8 @@
  */
 #define FULL_REGS(regs)		(((regs)->trap & 1) == 0)
 #ifndef __powerpc64__
-#define IS_CRITICAL_EXC(regs)	(((regs)->trap & 2) == 0)
+#define IS_CRITICAL_EXC(regs)	(((regs)->trap & 2) != 0)
+#define IS_MCHECK_EXC(regs)	(((regs)->trap & 4) != 0)
 #endif /* ! __powerpc64__ */
 #define TRAP(regs)		((regs)->trap & ~0xF)
 #ifdef __powerpc64__