efs: clean up -Wunused-const-variable= warning

When building with W=1, the following warning occurs.

In file included from fs/efs/super.c:18:0:
fs/efs/efs.h:22:19: warning: `cprt' defined but not used [-Wunused-const-variable=]
 static const char cprt[] = "EFS: "EFS_VERSION" - (c) 1999 Al Smith
<[email protected]>";
                   ^~~~
The 'cprt' is not used in any files, we move the copyright statement
into the comment.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Zhu Wang <[email protected]>
Cc: Al Smith <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

fs/efs/efs.h

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * Copyright (c) 1999 Al Smith
+ * Copyright (c) 1999 Al Smith, <[email protected]>
  *
  * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
  * Portions derived from IRIX header files (c) 1988 Silicon Graphics
@@ -19,9 +19,6 @@
 
 #define EFS_VERSION "1.0a"
 
-static const char cprt[] = "EFS: "EFS_VERSION" - (c) 1999 Al Smith <[email protected]>";
-
-
 /* 1 block is 512 bytes */
 #define	EFS_BLOCKSIZE_BITS	9
 #define	EFS_BLOCKSIZE		(1 << EFS_BLOCKSIZE_BITS)