ionic: flatten calls to set-rx-mode

Since only two functions call through ionic_set_rx_mode(), one
that can sleep and one that can't, we can split the function
and put the bits of code into the callers.  This removes an
unnecessary calling layer.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>