usb_bam: Update checking for producer and consumer client handler

Current code assumes that IPA producer and consumer client handler
can't be assigned as zero which is not true as zero as index is
valid. Hence check both producer and consumer client handler index
against -1 instead of zero.

This change also debug information about producer and consumer
client handler from usb_bam_disconnect_ipa() API.

Change-Id: I98838f7cba2aa625ee70cdc2a187cfbc822c0b43
Signed-off-by: Mayank Rana <mrana@codeaurora.org>