usb: misc: ks_bridge: handle multiple ksb devices enumeration

Driver currently supports enumeration of only one KSB device
connected at a time. Add changes to allow upto four KSB devices
enumeration and update the dev name with suffix to reflect the
HUB port to which they are connected for user to distinguish
between them.

CRs-fixed: 2009286
Change-Id: Ieee6c4d3d0a2ee35d9848b31cdd7038927fad95c
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>