[CRYPTO] camellia: Move more common code into camellia_setup_tail

Analogously to camellia7 patch, move
"absorb kw2 to other subkeys" and "absorb kw4 to other subkeys"
code parts into camellia_setup_tail(). This further reduces
source and object code size at the cost of two brances
in key setup code.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>