TQM885D: Exchanged SDRAM timing by a more relaxed timing.

CAS-Latency=2, Write Recovery Time tWR=2
The max. supported bus frequency is 66 MHz. Therefore, changed
threshold to switch from 1:1 mode to 2:1 from 80 MHz to 66 MHz.

Signed-off-by: Martin Krause <martin.krause@tqs.de>