Merge branch 'net-stmmac-prevent-div-by-0'

Alexis Lothoré says:

====================
net: stmmac: prevent div by 0

fix a small splat I am observing on a STM32MP157 platform at boot
(see commit 1) due to a division by 0.

v3: https://lore.kernel.org/20250528-stmmac_tstamp_div-v3-0-b525ecdfd84c@bootlin.com
v2: https://lore.kernel.org/20250527-stmmac_tstamp_div-v2-1-663251b3b542@bootlin.com
v1: https://lore.kernel.org/20250523-stmmac_tstamp_div-v1-1-bca8a5a3a477@bootlin.com
====================

Link: https://patch.msgid.link/20250529-stmmac_tstamp_div-v4-0-d73340a794d5@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>