net: ibm: emac: remove all waiting code

EPROBE_DEFER, which probably wasn't available when this driver was
written, can be used instead of waiting manually.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://patch.msgid.link/20240912024903.6201-9-rosenp@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>