Add support for an array of hwresets

[andrew]

Summary

In some drivers we need to assert and deassert a group of hardware
resets in any order. To support this add a new hwreset_array that
manages all hwresets defined for a device.

[manu]

sys/dev/extres/hwreset/hwreset_array.c

121

Wouldn't ENOMEM would be better ?

[andrew]

sys/dev/extres/hwreset/hwreset_array.c

121

It should be removed. I thought mallocarray could return NULL on overflow, but it calls panic.

[manu]

sys/dev/extres/hwreset/hwreset_array.c

121

Ok, good for me then.

[andrew]

Remove unneeded NULL check

[bz]

sys/dev/extres/hwreset/hwreset_array.c

129

You don't need the { } and you could just for (; i >= 0; i--) probably?

[mmel]

LGTM