usb: usb_bam: set pipe_connect->enabled status to false

Currently pipe_connect->enabled is not being set to false
on pipe disconnect for UL SYS2BAM path. Hence on next composition
required UL SYS2BAM pipe is not available or being configured which
causes device to crash. Hence set pipe_connect->enabled to false
on successful pipe disconnect.

CRs-Fixed: 601439
Change-Id: I126fe29f2d81fd4b846e0a6c1fc48373a4665093
Signed-off-by: Mayank Rana <mrana@codeaurora.org>