selftests: forwarding: update PTP tcpdump patterns

selftests: forwarding: update PTP tcpdump patterns

Recent version of tcpdump (tcpdump-4.99.6-1.fc43.x86_64) seems to have
removed the spurious space after msg type in PTP info, e.g.:

 before:  PTPv2, majorSdoId: 0x0, msg type : sync msg, length: 44
 after:   PTPv2, majorSdoId: 0x0, msg type: sync msg, length: 44

Update our patterns to match both.

Reviewed-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://patch.msgid.link/20260107145320.1837464-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>