ionic: flatten calls to ionic_lif_rx_mode

The _ionic_lif_rx_mode() is only used once and really doesn't
need to be broken out.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>