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 crash.
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>