[POWERPC] Never panic when taking altivec exceptions from userspace

At the moment we rely on a cpu feature bit or a firmware property to
detect altivec. If we dont have either of these and the cpu does in fact
support altivec we can cause a panic from userspace.

It seems safer to always send a signal if we manage to get an 0xf20
exception from userspace.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
void unknown_exception(struct pt_regs *regs)
{
	printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
	       regs->nip, regs->msr, regs->trap);

	_exception(SIGTRAP, regs, 0, 0);
}

void unknown_exception(struct pt_regs *regs)
{
	printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
	       regs->nip, regs->msr, regs->trap);

	_exception(SIGTRAP, regs, 0, 0);
}
