sunrpc/auth_gss: fix decoder callback prototypes

Declare the p_decode callbacks with the proper prototype instead of
casting to kxdrdproc_t and losing all type safety.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/net/sunrpc/auth_gss/gss_rpc_upcall.c b/net/sunrpc/auth_gss/gss_rpc_upcall.c
index 45ab924..a80b8e6 100644
--- a/net/sunrpc/auth_gss/gss_rpc_upcall.c
+++ b/net/sunrpc/auth_gss/gss_rpc_upcall.c
@@ -56,7 +56,7 @@ enum {
 [GSSX_##proc] = {					\
 	.p_proc   = GSSX_##proc,			\
 	.p_encode = gssx_enc_##name,	\
-	.p_decode = (kxdrdproc_t)gssx_dec_##name,	\
+	.p_decode = gssx_dec_##name,	\
 	.p_arglen = GSSX_ARG_##name##_sz,		\
 	.p_replen = GSSX_RES_##name##_sz, 		\
 	.p_statidx = GSSX_##proc,			\