crypto: nx - add NX-842 platform frontend driver

Add NX-842 frontend that allows using either the pSeries platform or
PowerNV platform driver (to be added by later patch) for the NX-842
hardware.  Update the MAINTAINERS file to include the new filenames.
Update Kconfig files to clarify titles and descriptions, and correct
dependencies.

Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/drivers/crypto/nx/Makefile b/drivers/crypto/nx/Makefile
index 8669ffa..5d9f4bc 100644
--- a/drivers/crypto/nx/Makefile
+++ b/drivers/crypto/nx/Makefile
@@ -11,4 +11,6 @@
 		  nx-sha512.o
 
 obj-$(CONFIG_CRYPTO_DEV_NX_COMPRESS) += nx-compress.o
-nx-compress-objs := nx-842-pseries.o
+obj-$(CONFIG_CRYPTO_DEV_NX_COMPRESS_PSERIES) += nx-compress-pseries.o
+nx-compress-objs := nx-842.o
+nx-compress-pseries-objs := nx-842-pseries.o