powerpc: Add alignment handler for new lfiwzx instruction

lfiwzx is a new floating point load instruction in 2.06 that needs an
alignment handler for Linux.

Turns out to be the worlds easiest handler to add.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>