external/fwts: fix regex generation for %p format
external/fwts: fix regex generation for %p format

Currently, we're emitting a non-grouping bracket expression for %p
formats, which isn't supported by regex(7). This change uses the
grouping format instead. The creation of a group has no effect in the
fwts olog code, so this should have no consequence on matches.

Signed-off-by: Jeremy Kerr <68a658b44bbaefab3ef5cd231967195fc0ff9d69@ozlabs.org>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

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