uqmi: fix non-working PLMN selection

uqmi: fix non-working PLMN selection

The PLMN selection was reset when calling network-register, thus
rendering the sepcific selection of a carrier unapplied.

Set the PLMN selection after executing network-register. This seems to
cause the modem to re-select the carrier eventually.

That being said, qmi does allow the parameterization of the
network-register to include dpecific PLMN settings, however this is
currently not implemented in uqmi.

Signed-off-by: David Bauer <mail@david-bauer.net>