[S390] zcrypt: adjust speed rating between cex2 and pcixcc

Cards with lower speed rating are prefered. Thus change adjust the
speed rating of cex2c adapters to be prefered before pcixcc, although
they should not appear in the same machine anyway.

Signed-off-by: Felix Beck <felix.beck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>