i2c: sh_i2c: enable i2c_probe

Before this patch i2c_probe() always returned 0 and "i2c probe" command did not work properly.

Modify i2c_set_addr() to check TACK when waiting DTE and make i2c_probe() call this function.

Acked-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Tetsuyuki Kobayashi <koba@kmckk.co.jp>