net: stmmac: dwmac4: Account for the primary MAC address for UC filtering

net: stmmac: dwmac4: Account for the primary MAC address for UC filtering

[ Upstream commit 82187f42c014d22520b9c3c4e2cfb519223fb29b ]

The same filter slots are used to store the main MAC address as well as
the address for the unicast filter. Let's account for that when deciding
whether or not to use promisc when programming the UC list in hardware.

Fixes: 477286b53f55 ("stmmac: add GMAC4 core support")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260826140500.616466-4-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>