hostfs: rename do_rmdir() to hostfs_do_rmdir()

do_rmdir() is used in the VFS layer at fs/namei.c, so use a different
name in hostfs.

Cc: Jeff Dike <jdike@addtoit.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

fs/hostfs/hostfs_user.c

@@ -304,7 +304,7 @@ int do_mkdir(const char *file, int mode)
 	return 0;
 }
 
-int do_rmdir(const char *file)
+int hostfs_do_rmdir(const char *file)
 {
 	int err;