sh: ms7724: Correct sh-eth EEPROM polling timeout.

This converts the cpu_relax() to a udelay(1), which fixes up issues with
the EEPROM polling occasionally timing out.

Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>