Introduce  helper functions that can initialize the bits in the AMR,
IAMR and UAMOR register; the bits that correspond to the given pkey.
Reviewed-by: NThiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: NRam Pai <linuxram@us.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>