net: mv643xx_eth: Simplify mv643xx_eth_adjust_link()

Currently, mv643xx_eth_adjust_link() is only used to call mv643xx_adjust_pscr().
This commit renames the latter to the former, and therefore removes the extra
and useless function.

Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>