staging/lustre: Fix sparse error (signature mismatch)

lprocfs_wr_atomic is defined in
drivers/staging/lustre/lustre/obdclass/lprocfs_status.c with its second argument
with the __user attribute:

int lprocfs_wr_atomic(struct file *file, const char __user *buffer,
              unsigned long count, void *data)

but its declaration in drivers/staging/lustre/lustre/include/lprocfs_status.h does
not include the attribute. Make declaration and definition match.
Signed-off-by: NL. Alberto Giménez <agimenez@sysvalve.es>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/include/lprocfs_status.h

@@ -604,7 +604,7 @@ extern int lprocfs_obd_seq_create(struct obd_device *dev, const char *name,
 
 extern int lprocfs_rd_u64(struct seq_file *m, void *data);
 extern int lprocfs_rd_atomic(struct seq_file *m, void *data);
-extern int lprocfs_wr_atomic(struct file *file, const char *buffer,
+extern int lprocfs_wr_atomic(struct file *file, const char __user *buffer,
 			     unsigned long count, void *data);
 extern int lprocfs_rd_uint(struct seq_file *m, void *data);
 extern int lprocfs_wr_uint(struct file *file, const char *buffer,