fotg210-udc: Mask GRP2 interrupts we don't handle

fotg210-udc: Mask GRP2 interrupts we don't handle

[ Upstream commit 9aee3a23d6455200702f3a57e731fa11e8408667 ]

Currently it leaves unhandled interrupts unmasked, but those are never
acked. In the case of a "device idle" interrupt, this leads to an
effectively frozen system until plugging it in.

Fixes: b84a8dee23fd ("usb: gadget: add Faraday fotg210_udc driver")
Signed-off-by: Fabian Vogt <fabian@ritter-vogt.de>
Link: https://lore.kernel.org/r/20210324141115.9384-5-fabian@ritter-vogt.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>