nfsd41: define NFSD_DRC_SIZE_SHIFT in set_max_drc

Fixes the following compiler error:
fs/nfsd/nfssvc.c: In function 'set_max_drc':
fs/nfsd/nfssvc.c:240: error: 'NFSD_DRC_SIZE_SHIFT' undeclared

CONFIG_NFSD_V4 is not set
Reported-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/nfssvc.c

@@ -236,6 +236,8 @@ void nfsd_reset_versions(void)
  */
 static void set_max_drc(void)
 {
+	/* The percent of nr_free_buffer_pages used by the V4.1 server DRC */
+	#define NFSD_DRC_SIZE_SHIFT	7
 	nfsd_serv->sv_drc_max_pages = nr_free_buffer_pages()
 						>> NFSD_DRC_SIZE_SHIFT;
 	nfsd_serv->sv_drc_pages_used = 0;

include/linux/nfsd/nfsd.h

@@ -333,9 +333,6 @@ extern struct timeval	nfssvc_boot;
 #define NFSD_LEASE_TIME                 (nfs4_lease_time())
 #define NFSD_LAUNDROMAT_MINTIMEOUT      10   /* seconds */
 
-/* The percent of nr_free_buffer_pages used by the V4.1 server DRC */
-#define NFSD_DRC_SIZE_SHIFT	7
-
 /*
  * The following attributes are currently not supported by the NFSv4 server:
  *    ARCHIVE       (deprecated anyway)