net: stmmac: dwmac1000: Account for the primary MAC address for UC filtering

net: stmmac: dwmac1000: Account for the primary MAC address for UC filtering

[ Upstream commit 9698b6da3714fd2ef47846cb63098d2b2d252e25 ]

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: 47dd7a540b8a ("net: add support for STMicroelectronics Ethernet controllers.")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260826140500.616466-3-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>