flash: Increase the maximum number of flash devices
flash: Increase the maximum number of flash devices

Increase the max number of flash devices from 1 to 8.

With mambo bogusdisk, we can have many flash devices.

Signed-off-by: Michael Neuling <7b0ab45a730e48a69239010b5b8fe5fa4e8eaac6@neuling.org>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

legoater/skiboot,open-power/skiboot,shenki/skiboot,open-power/skiboot,qemu/skiboot,mikey/skiboot,qemu/skiboot,qemu/skiboot,legoater/skiboot,mikey/skiboot,open-power/skiboot,stewart-ibm/skiboot,shenki/skiboot,qemu/skiboot,stewart-ibm/skiboot,qemu/skiboot,shenki/skiboot,shenki/skiboot,open-power/skiboot,legoater/skiboot,mikey/skiboot,legoater/skiboot,stewart-ibm/skiboot,open-power/skiboot,shenki/skiboot,legoater/skiboot