drivers: rmnet: perf: Dont flush on ps on

When we flush flow nodes during power save mode
on notification callback we risk encoutnering a race
condition where we are freeing buffers in rx context
and concurrently attempting to flush nonsense flow
nodes in wq context due to flow node indication from qmi

Change-id: Iba77bdb9adc10a18c3f536d6a866cc30ebcc2bb2
Signed-off-by: Conner Huff <chuff@codeaurora.org>