r8169: prevent excessive busy-waiting

r8169: prevent excessive busy-waiting

The MII registers read/write function blindly busy waits for an
amount of 1000 us (1 ms), then up to 200 ms. These functions are
called from irq disabled context. Depending on the clock management,
it triggers lost ticks events. Since the value is way above the
standard delay required for mii register access, it strangely looks
like a bandaid against posted writes.

Fixes http://bugzilla.kernel.org/show_bug.cgi?id=5947

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>