USB: phy-msm-usb: Fix unclocked access during disconnect in qdss mode

when cable is disconnected in qdss composition, qdss driver will
queue disconnect work as part of qdss_disable() and doesn't wait
till the disconnect work is completed. This results in crash if
disconnect work is scheduled after USB enters low power mode. Fix
the issue by checking whether usb bam pipe is disconnected or not
and if it is not disconnected, don't allow low power mode and
instead schedule suspend later.

CRs-Fixed: 678631
Change-Id: I72ef57fc4a04407f624fa73cd5abc12f5df3fecc
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>