msm: ipa: disconnect sequence change for USB 2.0

For USB 2.0 there is a requirement to not to flush the
USB endpoints after the pipes are disconnected. Otherwise
this can result into NOC errors. Make a change to modify the
disconnect sequence as below.

1) USB driver first disable the pipes
2) New API is provided from IPA to disable the endpoint.
3) As part of disable, make sure pipes are empty and reset
the pipes.
4) USB resets its BAM and flushes the ep.
5) USB then disconnects both IPA and USB pipes.

Change-Id: I917f025678e6abb03058d5be4ec42d9e6d76835f
Acked-by: Chaitanya Pratapa <cpratapa@qti.qualcomm.com>
Signed-off-by: Utkarsh Saxena <usaxena@codeaurora.org>