crypto/nx: Register and unregister VAS interface on PowerVM

The user space uses /dev/crypto/nx-gzip interface to setup VAS
windows, create paste mapping and close windows. This patch adds
changes to create/remove this interface with VAS register/unregister
functions on PowerVM platform.

Signed-off-by: Haren Myneni <[e-mail]>
Acked-by: Herbert Xu <[e-mail]>
Acked-by: Nicholas Piggin <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/crypto/nx/Kconfig

···
 config CRYPTO_DEV_NX_COMPRESS_PSERIES
 	tristate "Compression acceleration support on pSeries platform"
 	depends on PPC_PSERIES && IBMVIO
+	depends on PPC_VAS
 	default y
 	help
 	  Support for PowerPC Nest (NX) compression acceleration. This

drivers/crypto/nx/nx-common-pseries.c

···
 		return ret;
 	}
 
+	ret = vas_register_api_pseries(THIS_MODULE, VAS_COP_TYPE_GZIP,
+				       "nx-gzip");
+
+	if (ret)
+		pr_err("NX-GZIP is not supported. Returned=%d\n", ret);
+
 	return 0;
 }
 
···
 {
 	struct nx842_devdata *old_devdata;
 	unsigned long flags;
+
+	vas_unregister_api_pseries();
 
 	crypto_unregister_alg(&nx842_pseries_alg);