Fixed the sysctl in case of stderr errors

In case of errors and combine of stderr&stdout output of sysctl
the output gets broken and can't be parsed:

kernel.shmmni = 4096
kernel.shmerror: permission denied on key 'vm.compact_memory'
_rmid_forced = 0
kernel.msgmax = 8192
--
net.ipv4.route.gc_min_interval = 0
net.iperror: permission denied on key 'net.ipv4.route.flush'
v4.route.gc_min_interval_ms = 500
--
net.ipv6.conf.default.max_desync_factor = 600
net.ipv6.conf.default.max_addresses =error: permission denied on key 'net.ipv6.route.flush'
 16
net.ipv6.conf.default.accept_ra_defrtr = 1