octeontx2-af: Remove redundant functions mac2u64() and cfg2mac()

octeontx2-af: Remove redundant functions mac2u64() and cfg2mac()

The mac2u64() is used to convert an Ethernet MAC address into a u64 value,
as this is exactly what ether_addr_to_u64() does. Similarly, the cfg2mac()
is also the case. Use ether_addr_to_u64() and u64_to_ether_addr() instead
of these two.

Signed-off-by: Li Zetao <lizetao1@huawei.com>
Acked-by: Geethasowjanya Akula <gakula@marvell.com>
Link: https://lore.kernel.org/r/20230808114504.4036008-2-lizetao1@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>