usb: usb_bam: correctly access arrays using bam type as index

This commit improve code quality in the usb bam module.
In this commit we correctly handle the bam type property
of bam pipes in order to protect access to arrays that
use this property as index.

Change-Id: Iaefd72ec4b49b6fa731541a842ee665abc93cac5
CRs-Fixed: 535640
Signed-off-by: Ido Shayevitz <idos@codeaurora.org>