dwc2_hc_n_intr() writes back INTMASK as read but evaluates it
with intmask applied. In stress testing this causes spurious
interrupts like this:

[Mon Aug 14 10:51:07 2023] dwc2 3f980000.usb: dwc2_hc_chhltd_intr_dma: Channel 7 - ChHltd set, but reason is unknown
[Mon Aug 14 10:51:07 2023] dwc2 3f980000.usb: hcint 0x00000002, intsts 0x04600001
[Mon Aug 14 10:51:08 2023] dwc2 3f980000.usb: dwc2_hc_chhltd_intr_dma: Channel 0 - ChHltd set, but reason is unknown
[Mon Aug 14 10:51:08 2023] dwc2 3f980000.usb: hcint 0x00000002, intsts 0x04600001
[Mon Aug 14 10:51:08 2023] dwc2 3f980000.usb: dwc2_hc_chhltd_intr_dma: Channel 4 - ChHltd set, but reason is unknown
[Mon Aug 14 10:51:08 2023] dwc2 3f980000.usb: hcint 0x00000002, intsts 0x04600001
[Mon Aug 14 10:51:08 2023] dwc2 3f980000.usb: dwc2_update_urb_state_abn(): trimming xfer length

Applying INTMASK prevents this. The issue exists in all versions of the
driver.
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Tested-by: Ivan Ivanov <ivan.ivanov@suse.com>
Tested-by: Andrea della Porta <andrea.porta@suse.com>
Link: https://lore.kernel.org/r/20231115144514.15248-1-oneukum@suse.com
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>