ARM: vf610: ddrmc: fix initialization completion detection

The CR80 register has multiple interrupt bits, the code is supposed
to check bit 8 but instead uses a logical and. In most cases this
probably did not affect real operations since at that stage typically
none of the other bits are set.

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Acked-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>