smsc911x: add second read of EEPROM mac when possible corruption seen

smsc911x: add second read of EEPROM mac when possible corruption seen

When the EEPROM MAC is read by way of ADDRH, it can return all 0s the
first time. Subsequent reads succeed.

This is fully reproduceable on the Phytec PCM049 SOM.

Re-read the ADDRH when this behaviour is observed, in an attempt to
correctly apply the EEPROM MAC address.

Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
Link: https://patch.msgid.link/20250903132610.966787-1-colin.foster@in-advantage.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>