usb_bam: Enable flow control in IPA if disabled during disconnect

On some platforms, there is a chance flow control has been disabled
from IPA side due to which IPA can't consume data till it got cleared.
If USB disconnect happens, USB driver waits for sps pipe to be empty
for 10 msec and if it is not empty, USB injects ZLT descriptor on IPA
BAM by calling SPS driver API. Even after this, USB->IPA pipe will not
empty if flow control is disabled and triggers panic. Hence explicitly
call IPA driver API to enable flow control for removing delay on
IPA endpoint for USB->IPA pipe to fix this.

Change-Id: I321052ebdec600325517dbccc13b02788f491744
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>