net: enetc: don't depend on system endianness in enetc_set_mac_ht_flt

When enetc runs out of exact match entries for unicast address
filtering, it switches to an approach based on hash tables, where
multiple MAC addresses might end up in the same bucket.

However, the enetc_set_mac_ht_flt function currently depends on the
system endianness, because it interprets the 64-bit hash value as an
array of two u32 elements. Modify this to use lower_32_bits and
upper_32_bits.

Tested by forcing enetc to go into hash table mode by creating two
macvlan upper interfaces:

ip link add link eno0 address 00:01:02:03:00:00 eno0.0 type macvlan && ip link set eno0.0 up
ip link add link eno0 address 00:01:02:03:00:01 eno0.1 type macvlan && ip link set eno0.1 up

and verified that the same bit values are written to the registers
before and after:

enetc_sync_mac_filters: addr 00:00:80:00:40:10 exact match 0
enetc_sync_mac_filters: addr 00:00:00:00:80:00 exact match 0
enetc_set_mac_ht_flt: hash 0x80008000000000 UMHFR0 0x0 UMHFR1 0x800080

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>