MAINTAINERS: adjust file entries after crypto vmx file movement

Commit 10930333

 ("crypto: vmx - Move to arch/powerpc/crypto") moves the
crypto vmx files to arch/powerpc, but misses to adjust the file entries for
IBM Power VMX Cryptographic instructions and LINUX FOR POWERPC.

Hence, ./scripts/get_maintainer.pl --self-test=patterns complains about
broken references.

Adjust these file entries accordingly. To keep the matched files exact
after the movement, spell out each file name in the new directory.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>