USB: gadget: Fix USB EP flush issues on disconnect

Currently if cable is disconnected or composition switch happens
during BAM2BAM data transfers, USB driver tries to flush USB
endpoint as part of disconnect, which is failing. This eventually
leads to NOC error. Fix the issue by making sure pipes are empty
and IPA endpoints are disabled and perform USB bam reset before
disabling USB endpoints as part of new sequence implementation
recommended by HW designers.

Change-Id: I17000fd380d95497629372a9f6371902f04ca2d9
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>