dt-bindings: ufs: Add #reset-cells for Qualcomm controllers

Enable Qualcomm UFS controllers to expose the PHY reset via a reset
controller.

Signed-off-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>