net: ravb: Assert/de-assert reset on suspend/resume

RZ/G3S can go to deep sleep states where power to most of the SoC parts is
off. When resuming from such a state, the Ethernet controller needs to be
reinitialized. De-asserting the reset signal for it should also be done.
Thus, add reset assert/de-assert on suspend/resume functions.

On the resume function, the de-assert was not reverted in case of failures
to give the user a chance to restore the interface (e.g., bringing down/up
the interface) in case suspend/resume failed.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>