ahci: qoriq: Update the default Rx watermark value
The PTC[RXWM] sets the watermark value for Rx FIFO. The default
value 0x20 might be insufficient for some hard drives. If the
watermark value is too small, a single-cycle overflow may occur
and is reported as a CRC or internal error in the PxSERR register.
Updated the value to 0x29 according to the validation test.
All LS platforms are affected.