dhcpcd: bump to 6.11.5

1.) pkg version bumped from 6.4.3 to 6.11.5
2.) maintainer changed to me (#4944 dhcpcd: needs a new maintainer)
3.) source changed from bz2 to xz
4.) removed old unnecessary patch
5.) minor style improvements

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>