ARMv7: Branch over conditional undefined instructions in vfphw.S

On ARMv7, conditional undefined instructions may generate exceptions
even if the condition is not met. The vfphw.S contains the FPINST and
FPINST2 access instructions which may not be present on processors with
synchronous VFP exceptions.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>