NFSv4.2: Move TRACE_DEFINE_ENUM(NFS4_CONTENT_*) under CONFIG_NFS_V4_2

NFS4_CONTENT_DATA and NFS4_CONTENT_HOLE both only exist under NFS v4.2.
Move their corresponding TRACE_DEFINE_ENUM calls under this Kconfig
option.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4trace.h

@@ -2097,6 +2097,7 @@ TRACE_EVENT(ff_layout_commit_error,
 		)
 );
 
+#ifdef CONFIG_NFS_V4_2
 TRACE_DEFINE_ENUM(NFS4_CONTENT_DATA);
 TRACE_DEFINE_ENUM(NFS4_CONTENT_HOLE);
 
@@ -2105,7 +2106,6 @@ TRACE_DEFINE_ENUM(NFS4_CONTENT_HOLE);
 		{ NFS4_CONTENT_DATA, "DATA" },		\
 		{ NFS4_CONTENT_HOLE, "HOLE" })
 
-#ifdef CONFIG_NFS_V4_2
 TRACE_EVENT(nfs4_llseek,
 		TP_PROTO(
 			const struct inode *inode,