netfilter: ip6t_NPT: fix IPv6 NTP checksum calculation
netfilter: ip6t_NPT: fix IPv6 NTP checksum calculation

csum16_add() has a broken carry detection, should be:
sum += sum < (__force u16)b;

Instead of fixing csum16_add, remove the custom checksum
functions and use the generic csum_add/csum_sub ones.

Signed-off-by: Ulrich Weber <83d9ef8f6b70f27b158856816e437cdb46d8111d@sophos.com>
Acked-by: Patrick McHardy <3a4d625ce225e891399f98db96a382ac4a84080b@trash.net>
Signed-off-by: Pablo Neira Ayuso <707d14912bb250caf67dfe0ea4035681fbfc4f56@netfilter.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas