Fix probable prime confidence calculations.

This fix from upstream fixes a problem where the number of iterations
used to confirm that a number is prime was based off the length of the
key rather than the length of the factors p and q.  Fewer iterations
are called for for a longer number, so this resulted in a
lower-than-expected confidence in the primality of the key factors.

This only affects apps that use RSAKeyPairGenerator directly (which is
not a public API), rather than those that use
java.security.KeyPairGenerator.

Upstream commits:

https://github.com/bcgit/bc-java/commit/73780ac522b7795fc165630aba8d5f5729acc839
https://github.com/bcgit/bc-java/commit/22467b6e8fe19717ecdf201c0cf91bacf04a55ad

Bug: 79148652
Test: make
Change-Id: I759a226afc9dbd948611eed99ad89ab7f59b09f8
(cherry picked from commit 91719e3c1be2eb206a50a49a5d172884d65eba1c)