mesh: Fix provisioning with Key Refresh flag set
mesh: Fix provisioning with Key Refresh flag set

We should not have any valid key material in key slot 0 if the KR flag
is set, since then the new key/old key information will be incorrect
when network PDUs get decrypted.

X-Original-Commit: be8250d36a5401c4bf6e9ce6340285deccb5628c

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble