Quieten SLW log messages, mostly to PR_DEBUG. Some elevated to PR_ERR/WARN
Quieten SLW log messages, mostly to PR_DEBUG. Some elevated to PR_ERR/WARN

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

shenki/skiboot,legoater/skiboot,legoater/skiboot,jk-ozlabs/skiboot,shenki/skiboot,legoater/skiboot,ddstreet/skiboot,legoater/skiboot,cyrilbur-ibm/skiboot,mikey/skiboot,shenki/skiboot,qemu/skiboot,csmart/skiboot,neelegup/skiboot,csmart/skiboot,neelegup/skiboot,ddstreet/skiboot,stewart-ibm/skiboot,stewart-ibm/skiboot,qemu/skiboot,open-power/skiboot,open-power/skiboot,shenki/skiboot,apopple/skiboot,mikey/skiboot,open-power/skiboot,cyrilbur-ibm/skiboot,stewart-ibm/skiboot,mikey/skiboot,jk-ozlabs/skiboot,apopple/skiboot,qemu/skiboot,legoater/skiboot,qemu/skiboot,ddstreet/skiboot,apopple/skiboot,cyrilbur-ibm/skiboot,qemu/skiboot,csmart/skiboot,neelegup/skiboot,shenki/skiboot,open-power/skiboot,open-power/skiboot,jk-ozlabs/skiboot