usb: bam: don't wait to enable/disable endpoints on bam2bam work functions

Enable or disable the endpoints, also in case of bam2bam connection,
at the gbam_connect and gbam_disconnect APIs, rather then in the
bam2bam work functions.

This change fixes a race condition when there is a pending disconnect
in the bam2bam port's workqueue, therefore endpoints were not disabled
yet, while frmnet_set_alt is checking the state of the endpoints, which
are still enabled, therefore not queuing a connect work.

Change-Id: Ibc2eb9b8a747061c52132dbc112ce5e5525adc2c
CRs-Fixed: 397466
Signed-off-by: Ido Shayevitz <idos@codeaurora.org>