MFC r299503,r299504:

r299503 (by cem):

snd_hda(4): Don't pass bogus sizeof()s to unused sysctl arg2 parameter

None of the sysctl handlers in hdaa use the arg2 parameter, so just pass zero
instead. Additionally, the sizes being passed in were suspect (size of the
pointer rather than the value).

CIDs: 1007694, 1009679

r299504 (by cem):

snd_hda(4): Don't pass bogus sizeof()s to unused sysctl arg2 parameter (again)

More of the same sort of issue as r299503, just missed some sysctls added in a
different place than the others.

CIDs: 1007692, 1009677, 1009678