net: gem: Check if phy was correctly detected

As tsec and fm drivers checking phydev->link
ensure that u-boot don't try access device if link is not ready.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
i2c, zynq: convert zynq i2c driver to new multibus/multiadapter framework

- add zync i2c driver to new multibus/multiadpater support
- adapted all config files, which uses this driver

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Michal Simek <michal.simek@xilinx.com>

This is backport from mainline mainly for testing purpose.
Makefile changes and zynq_common.h changes have been made.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>