phy: cadence: Sierra: Explicitly request exclusive reset control

No functional change. Since the reset controls obtained in
Sierra is exclusively used by the Sierra device, use
exclusive reset control request API calls.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20210319124128.13308-8-kishon@ti.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>