powerpc/crypto: don't build aes-gcm-p10 by default

None of the other accelerated crypto modules are built by default.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/40d9c7ebe82c9a9d4ace542ac433753d2f22c6a0.1689007370.git.osandov@osandov.com