crypto: omap-aes - select BLKCIPHER2

without it:
|drivers/built-in.o:(.data+0x14588): undefined reference to `crypto_ablkcipher_type'
|drivers/built-in.o:(.data+0x14668): undefined reference to `crypto_ablkcipher_type'

Not sure when this broke.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>