selftests: tc-testing: prefix iproute2 functions with "ipr2"

As suggested by Simon, prefix the functions that operate on iproute2
commands in contrast with the "nl" netlink prefix.

Cc: Simon Horman <horms@kernel.org>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20231124154248.315470-4-pctammela@mojatatu.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>