net: sun8i_emac: Fix MAC soft reset

The EMAC soft reset routine was subtly broken, using an open coded
timeout routine without any actual delay.
Remove the unneeded initial reset bit read, and call wait_for_bit_le32()
to handle the timeout correctly.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Amit Singh Tomar <amittomer25@gmail.com> # Pine64+
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>