usb: musb: jz4740: Prevent lockup when CONFIG_SMP is set

usb: musb: jz4740: Prevent lockup when CONFIG_SMP is set

The function dma_controller_irq() locks up the exact same spinlock we
locked before calling it, which obviously resulted in a deadlock when
CONFIG_SMP was enabled. This flew under the radar as none of the boards
supported by this driver needs SMP.

Fixes: 738e02ae25bd ("usb: musb: jz4740: Add support for DMA")
Cc: stable@vger.kernel.org
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Bin Liu <b-liu@ti.com>
Link: https://lore.kernel.org/r/20200525025049.3400-6-b-liu@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>