usb: u_data_ipa.c: Use already initialized BAM connection indexes

Driver already initializes src/dst_connection_idx on connect for
BAM2BAM transports, but, it still queries the same again. Fix this
by using existing src/dst_connect_idx.

Change-Id: I99747ad173fdcc3391c57dbea79dbe311f76396f
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>