crypto: nx - move nx build to driver/crypto Makefile

When the nx driver was pulled, the Makefile that actually
builds it is arch/powerpc/Makefile. This is unnatural.

This patch moves the line that builds the nx driver from
arch/powerpc/Makefile to drivers/crypto/Makefile where it
belongs.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Kent Yoder <key@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/Makefile

@@ -16,3 +16,4 @@ obj-$(CONFIG_CRYPTO_DEV_S5P) += s5p-sss.o
 obj-$(CONFIG_CRYPTO_DEV_TEGRA_AES) += tegra-aes.o
 obj-$(CONFIG_CRYPTO_DEV_UX500) += ux500/
 obj-$(CONFIG_CRYPTO_DEV_BFIN_CRC) += bfin_crc.o
+obj-$(CONFIG_CRYPTO_DEV_NX) += nx/