dwc3: core: Don't perform controller and PHYs soft reset

Controller and PHY soft reset may result in unknown flip-flop state
resulting in undefined issues. Soft reset is not required as
Controller and PHY are reset using GCC anyway.

Change-Id: I6c2eedd2642ff86b03cf47c97808e461ef5e8f41
Signed-off-by: Mayank Rana <mrana@codeaurora.org>