UPSTREAM: usb: dwc2: host: Add missing spinlock in dwc2_hcd_reset_func()

UPSTREAM: usb: dwc2: host: Add missing spinlock in dwc2_hcd_reset_func()

The dwc2_hcd_reset_func() function is only ever called directly by a
delayed work function.  As such no locks are already held when the
function is called.

Doing a read-modify-write of CPU registers and setting fields in the
main hsotg data structure is a bad idea without locks.  Let's add
locks.

The bug was found by code inspection only.  It turns out that the
dwc2_hcd_reset_func() is only ever called today if the
"host_support_fs_ls_low_power" parameter is enabled and no code in
mainline enables that parameter.  Thus no known issues in mainline are
fixed by this patch, but it's still probably wise to fix the function.

Change-Id: I14ff93f64f1fd405d4911d67c7d0b20e50be4f53
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Huang, Tao <huangtao@rock-chips.com>
(cherry picked from commit 4a065c7bdbec9536f7b899241b125b9c3b5ba97a)