NXP's mEMAC reference manual, Chapter 6.5.5 "MDIO Ethernet Management
Interface usage", specifies to poll the BSY (0) bit in the CFG/STAT
register to wait until a transaction has finished, not bit 31 in the
data register.

In the Linux kernel, this has already been fixed in commit 26eee0210ad7
("net/fsl: fix a bug in xgmac_mdio").

This patch changes the register in the fman_mdio and fsl_ls_mdio
drivers.

As the MDIO_DATA_BSY define is no longer in use, this patch also removes
its definition from the fsl_memac header.

Signed-off-by: Markus Koch <markus@notsyncing.net>
Reviewed-by: Camelia Groza <camelia.groza@nxp.com>