Merge branch 'introduce-read_poll_timeout'

Dejin Zheng says:

====================
introduce read_poll_timeout

This patch sets is introduce read_poll_timeout macro, it is an extension
of readx_poll_timeout macro. the accessor function op just supports only
one parameter in the readx_poll_timeout macro, but this macro can
supports multiple variable parameters for it. so functions like
phy_read(struct phy_device *phydev, u32 regnum) and
phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum) can
use this poll timeout framework.

the first patch introduce read_poll_timeout macro, and the second patch
redefined readx_poll_timeout macro by read_poll_timeout(), and the other
patches are examples using read_poll_timeout macro.

v6 -> v7:
	- add a parameter to supports that it can sleep some time
	  before read operation in read_poll_timeout macro.
	- add prefix with double underscores for some variable to avoid
	  any variable re-declaration or shadowing in patch 3 and patch
	  7.
v5 -> v6:
	- add some check to keep the code more similar in patch 8
v4 -> v5:
	- add some msleep() before call phy_read_mmd_poll_timeout() to
	  keep the code more similar in patch 6 and patch 9.
	- add a patch of drop by v4, it can add msleep before call
	  phy_read_poll_timeout() to keep the code more similar.
v3 -> v4:
	- add 3 examples of using new functions.
	- deal with precedence issues for parameter cond.
	- drop a patch about phy_poll_reset() function.
v2 -> v3:
	- modify the parameter order of newly added functions.
	  phy_read_mmd_poll_timeout(val, cond, sleep_us, timeout_us, \
				     phydev, devaddr, regnum)
				||
				\/
	  phy_read_mmd_poll_timeout(phydev, devaddr regnum, val, cond, \
				    sleep_us, timeout_us)

	  phy_read_poll_timeout(val, cond, sleep_us, timeout_us, \
				phydev, regnum)
				||
				\/
	  phy_read_poll_timeout(phydev, regnum, val, cond, sleep_us, \
				timeout_us)
v1 -> v2:
	- passed a phydev, device address and a reg to replace args...
	  parameter in phy_read_mmd_poll_timeout() by Andrew Lunn 's
	  suggestion in patch 3. Andrew Lunn <andrew@lunn.ch>, Thanks
	  very much for your help!
	- also in patch 3, handle phy_read_mmd return an error(the return
	  value < 0) in phy_read_mmd_poll_timeout(). Thanks Andrew
	  again.
	- in patch 6, pass a phydev and a reg to replace args...
	  parameter in phy_read_poll_timeout(), and also handle the
	  phy_read() function's return error.
====================

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