[aic7xxx] Use correct product name 29320LPE instead of non-existent 39320LPE

The PCI id belongs to Adaptec 29320LPE controller. The same fix also was
merged[1] to OpenBSD driver ~6 years ago.

[1] https://github.com/openbsd/src/commit/f997b5

PR: 172133
Submitted by: henning.petersen@t-online.de
MFC after: 1 week