net: dp83640: fix broken calibration routine.

commit 397a253a upstream.

Currently, the calibration function that corrects the initial offsets
among multiple devices only works the first time.  If the function is
called more than once, the calibration fails and bogus offsets will be
programmed into the devices.

In a well hidden spot, the device documentation tells that trigger indexes
0 and 1 are special in allowing the TRIG_IF_LATE flag to actually work.

This patch fixes the issue by using one of the special triggers during the
recalibration method.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/net/phy/dp83640.c

@@ -46,7 +46,7 @@
 #define PSF_TX		0x1000
 #define EXT_EVENT	1
 #define CAL_EVENT	7
-#define CAL_TRIGGER	7
+#define CAL_TRIGGER	1
 #define PER_TRIGGER	6
 #define DP83640_N_PINS	12