net/ncsi: Refactor MAC, VLAN filters

The NCSI driver defines a generic ncsi_channel_filter struct that can be
used to store arbitrarily formatted filters, and several generic methods
of accessing data stored in such a filter.
However in both the driver and as defined in the NCSI specification
there are only two actual filters: VLAN ID filters and MAC address
filters. The splitting of the MAC filter into unicast, multicast, and
mixed is also technically not necessary as these are stored in the same
location in hardware.

To save complexity, particularly in the set up and accessing of these
generic filters, remove them in favour of two specific structs. These
can be acted on directly and do not need several generic helper
functions to use.

This also fixes a memory error found by KASAN on ARM32 (which is not
upstream yet), where response handlers accessing a filter's data field
could write past allocated memory.

[  114.926512] ==================================================================
[  114.933861] BUG: KASAN: slab-out-of-bounds in ncsi_configure_channel+0x4b8/0xc58
[  114.941304] Read of size 2 at addr 94888558 by task kworker/0:2/546
[  114.947593]
[  114.949146] CPU: 0 PID: 546 Comm: kworker/0:2 Not tainted 4.16.0-rc6-00119-ge156398bfcad #13
...
[  115.170233] The buggy address belongs to the object at 94888540
[  115.170233]  which belongs to the cache kmalloc-32 of size 32
[  115.181917] The buggy address is located 24 bytes inside of
[  115.181917]  32-byte region [94888540, 94888560)
[  115.192115] The buggy address belongs to the page:
[  115.196943] page:9eeac100 count:1 mapcount:0 mapping:94888000 index:0x94888fc1
[  115.204200] flags: 0x100(slab)
[  115.207330] raw: 00000100 94888000 94888fc1 0000003f 00000001 9eea2014 9eecaa74 96c003e0
[  115.215444] page dumped because: kasan: bad access detected
[  115.221036]
[  115.222544] Memory state around the buggy address:
[  115.227384]  94888400: fb fb fb fb fc fc fc fc 04 fc fc fc fc fc fc fc
[  115.233959]  94888480: 00 00 00 fc fc fc fc fc 00 04 fc fc fc fc fc fc
[  115.240529] >94888500: 00 00 04 fc fc fc fc fc 00 00 04 fc fc fc fc fc
[  115.247077]                                             ^
[  115.252523]  94888580: 00 04 fc fc fc fc fc fc 06 fc fc fc fc fc fc fc
[  115.259093]  94888600: 00 00 06 fc fc fc fc fc 00 00 04 fc fc fc fc fc
[  115.265639] ==================================================================

Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>