ks8851: Changes to handle intermittent data stall

Due to updating the tx queue value to be 18k at every irq,
and using rx work queue in threaded irq context, the irq
for rx was raised in midway of data read, which lead to
wrong reading of packets and hence data stall.

Change-Id: I6d10952832ad1de351c0fc3579ca1b045a45d284
Acked-by: Rishav LNU <rna@qti.qualcomm.com>
Signed-off-by: Mohammed Javid <mjavid@codeaurora.org>