usb: musb: dsps: do not disable CPPI41 irq in driver teardown

TI AM335x CPPI 4.1 module uses a single register bit for CPPI interrupts
in both musb controllers. So disabling the CPPI irq in one musb driver
breaks the other musb module.

Since musb is already disabled before tearing down dma controller in
musb_remove(), it is safe to not disable CPPI irq in
musb_dma_controller_destroy().

Fixes: 25534828 ("usb: musb: dsps: Manage CPPI 4.1 DMA interrupt in DSPS")
Cc: stable@vger.kernel.org
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>