usb: functions: disconnect with UL using SYS2BAM

When calling the USB's function's disconnect function,
we are required to pass a private handle that was given
during the connection flow.
In cases where there is a need to use SYS2BAM connection
for the UL (UL workaround), this private handle is stored
in a different place in the port's ipa_param structure. This
fix selects the proper private handle, based on whether the
UL workaround was implemented.

CRs-Fixed: 607402, 605325
Change-Id: I10ba50451c802457dfa341bae4c2054d5bc0439d
Signed-off-by: Dov Levenglick <dovl@codeaurora.org>