samsung-klte: base downstream kernel on Android 7.1 branch and tidy/add some patches

@drebrez originally based klte port on lineage-16.0 branch (Android 9), but we need compatibility with Android 7.1, so use lineage-14.1 branch.

Also tidy up downstream kernel config a little bit (pass it through pmbootstrap kconfig edit, change nothing, exit with saving). (And also remove custom vendor OOM_KILLER)

• fix patch file names and reorder them properly
• add patch to fix framebuffer memory allocation
• add patch to fix compile warning for iptables plugin xt_connbytes
• add patch to properly assign MAC address for USB RNDIS
• add backport patch from upstream about O_PATH file descriptors