proc: spread "const" a bit

Link: http://lkml.kernel.org/r/20180627200614.GB18434@avx2
Signed-off-by: Alexey Dobriyan <[e-mail]>
Reviewed-by: Andrew Morton <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/proc/internal.h

···
 	return PDE(inode)->data;
 }
 
-static inline struct pid *proc_pid(struct inode *inode)
+static inline struct pid *proc_pid(const struct inode *inode)
 {
 	return PROC_I(inode)->pid;
 }
 
-static inline struct task_struct *get_proc_task(struct inode *inode)
+static inline struct task_struct *get_proc_task(const struct inode *inode)
 {
 	return get_pid_task(proc_pid(inode), PIDTYPE_PID);
 }

include/linux/proc_fs.h

···
 		   struct ns_common *(*get_ns)(struct ns_common *ns));
 
 /* get the associated pid namespace for a file in procfs */
-static inline struct pid_namespace *proc_pid_ns(struct inode *inode)
+static inline struct pid_namespace *proc_pid_ns(const struct inode *inode)
 {
 	return inode->i_sb->s_fs_info;
 }