usb: dwc3: gadget: clear SUSPHY bit before ep cmds

Upstream Linux commit 2b0f11df84bb.

Synopsys Databook 2.60a has a note that if we're
sending an endpoint command we _must_ make sure that
DWC3_GUSB2PHY(n).SUSPHY bit is cleared.

This patch implements that particular detail.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Link: https://lore.kernel.org/r/20240412202611.3565052-3-alexander.sverdlin@siemens.com


Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>