ahci: qoriq: correct the sata ecc setting error

Sata ecc is controlled by only 1 bit which is 24bit in big-endian
in ecc register. So only setting 24bit to disable sata ecc prevents
other bits from being overwritten in ecc register.

Signed-off-by: Tang Yuantian <andy.tang@nxp.com>
Signed-off-by: Tejun Heo <tj@kernel.org>