net: sched: avoid printing uninitialized link speed

net: sched: avoid printing uninitialized link speed

sch_cbs and sch_taprio print ecmd.base.speed, even if
netif_get_link_ksettings() failed. When netif_get_link_ksettings()
fails the ecmd may not be initialized.

Use the always-initialized speed variable instead.
The semantics change slightly because UNKNOWN will
never be printed, but that doesn't seem important
enough to complicate the code for.

This is a _dbg() print, anyway.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20260609183353.1109641-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>