remoteproc: k3-r5: Delay notification of wakeup event

commit 0adfbf6ba7de2e2c9c653ce8997ced3df0de7fa7 from
git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git



Few times, core 1 was scheduled to boot first before core0.
Which leads to error
'k3_r5_rproc_start: can not start core 1 before core 0'.

This was happening due to some scheduling between prepare
and start callback. The probe function waits for event,
which is getting triggered by prepare callback.

To avoid above condition move even trigger to start instead
of prepare callback.

Fixes: 7dcf3e00aa95 ("remoteproc: k3-r5: Wait for core0 power-up before powering up core1")
Cc: Rahul Ravikumar <r-ravikumar@ti.com>
Cc: Hari Nagalla <hnagalla@ti.com>
Signed-off-by: Udit Kumar <u-kumar1@ti.com>
Reviewed-by: Beleswar Padhi <b-padhi@ti.com>
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>