In fs/nfs/proc.c::nfs_proc_symlink() we will leak memory if either
nfs_alloc_fhandle() or nfs_alloc_fattr() returns NULL but the other one
doesn't.
This patch ensures memory allocated by one when the other fails is always
released (this is safe since nfs_free_fattr() and nfs_free_fhandle() both
call kfree which deals gracefully with NULL pointers).