The default timeout for tests is 45sec, bench-lookups_ipv6
seems to take around 50sec when running in a VM without
HW acceleration. Give it a 2x margin and set the timeout
to 120sec.

Fixes: d1066c9c ("selftests/net: Add test/benchmark for removing MKTs")
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Link: https://lore.kernel.org/r/20240124233630.1977708-1-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>