bit_and() uses the count of bits as the woking length.
Fix the previous implementation and effectively use
the right bitmap size.
Fixes: 19fd83a64718 ("KVM: s390: vsie: allow CRYCB FORMAT-1")
Fixes: 56019f9aca22 ("KVM: s390: vsie: Allow CRYCB FORMAT-2")
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>