vsnprintf: Change print_itoa to use less stack
vsnprintf: Change print_itoa to use less stack

Remove recursive call in print_itoa to reduce the stack usage.

Signed-off-by: Shreyas B. Prabhu <fac76aafe57fc9acb24e05f5dba9b58a43a0a645@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

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