net: qmi_wwan: fixup Sierra Wireless MC8305 entry

The MC8305 module got an additional entry added based solely on
information from a Windows driver *.inf file. We now have the
actual descriptor layout from one of these modules, and it
consists of two alternate configurations where cfg #1 is a
normal Gobi 2k layout and cfg #2 is MBIM only, using interface
numbers 5 and 6 for MBIM control and data. The extra Windows
driver entry for interface number 5 was most likely a bug.

Deleting the bogus entry to avoid unnecessary qmi_wwan probe
failures when using the MBIM configuration.

Reported-by: Lana Black <sickmind@lavabit.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>