powerpc/mm: Fix missing update of HID register on secondary CPUs

We need to update on secondaries for the selected MMU mode.

Fixes: ad410674 ("powerpc/mm: Update the HID bit when switching from radix to hash")
Reported-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>