ARM: vfp: Move exception address fixup into vfphw.S

If the PC on the stack is updated in entry-armv.S,
do_undefinstr can get called after the fixup.  do_undefinstr
does its own fixup, and doing both causes the PC to point to
half way through an instruction.

Instead, do the fixup in do_vfp, where only the vfp code
can get called.

Change-Id: I6d966887adc8ed58d88bfe0cb3c0ba29213be488
Signed-off-by: Colin Cross <ccross@android.com>