net: phy: use unlocked accessors for indirect MMD accesses

commit 1b2dea2e upstream.

Use unlocked accessors for indirect MMD accesses to clause 22 PHYs.
This permits tracing of these accesses.

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>