lib: rhashtable: Correct self-assignment in rhashtable.c

In file lib/rhashtable.c line 777, skip variable is assigned to
itself. The following error was observed:

lib/rhashtable.c:777:41: warning: explicitly assigning value of
variable of type 'int' to itself [-Wself-assign] error, forbidden
warning: rhashtable.c:777
This error was found when compiling with Clang 6.0. Change it to iter->skip.

Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>