ppc: Move exception generation code out of line

There's no point inlining this, if you hit the exception case you exit
anyway, and not inlining saves about 100K of code size (and cache
footprint).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[clg: removed '__attribute__((noinline))' from original patch ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>