generic: ar8216: move sleep out of the loop

It is enough to sleep once after ANEG is enabled on
all PHYs. This reduces boot time on boards with
AR8316 switch.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@35532 3c298f89-4303-0410-b956-a3cf2f4a3e73