Merge branch 'net-stmmac-Use-readl_poll_timeout-to-simplify-the-code'

Dejin Zheng says:

====================
net: stmmac: Use readl_poll_timeout() to simplify the code

This patch sets just for replace the open-coded loop to the
readl_poll_timeout() helper macro for simplify the code in
stmmac driver.

v2 -> v3:
	- return whatever error code by readl_poll_timeout() returned.
v1 -> v2:
	- no changed. I am a newbie and sent this patch a month
	  ago (February 6th). So far, I have not received any comments or
	  suggestion. I think it may be lost somewhere in the world, so
	  resend it.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>