uboot-imx

net: zynq: Fix MDC setting for zynq

Based on spec:
"MDC must not exceed 2.5 MHz (MDC is only active during MDIO read and
write operations)"
Zynq is running on 111MHz. Current setting is 32 which is 111/32=3.47
which is above of 2.5MHz.
Using 48 divider will give us correct setting according spec
(111/48=2.31).

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>