s390/pci: remove per device debug attribute

The per-pci-device 'debug' attribute is ill defined. For each device
it prints the same information, the adapter interrupt bit vector for
irq numbers 0 & 1, the start of the global interrupt summary vector
and the global irq retries counter. Just remove the attribute and
the associated code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>