usb: musb: Fix cppi_channel_abort() function to handle Tx abort correctly

This patch fixes the Tx abort/teardown logic. We now wait for the teardown
completion interrupt and acknowledge the same by setting the tx_complete
register to 0.

This change is needed to ensure that abort processing works on DM365 platform.
Without this change after completion of abort processing the system is
overwhelmed with continuous stream of abort interrupts.

This change has been tested on all CPPI3.x platforms (DM644x, DM646x, DM35x,
DM36x).

Signed-off-by: Swaminathan S <swami.iyer@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>