Fix potential negative loop bound in hdata/pcia.c
Fix potential negative loop bound in hdata/pcia.c

HDIF_get_iarray_size could return -1 on failure, so detect that
and somewhat gracefully back out of an awful loop

Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

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