Only print SPIRA discovered serial port info at PR_INFO priority
Only print SPIRA discovered serial port info at PR_INFO priority

It's certainly not an error that we have a serial port, and not
essential to display during boot. Odds are, you already know
about the serial port.

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

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