generic syscalls: wire up preadv2 and pwritev2 syscalls

These new syscalls are implemented as generic code, so enable them for
architectures like arm64 which use the generic syscall table.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
1 file changed