msm: msm_bus: send correct value to bw division function

While calculating bw for existing client request
sometimes it can go to negative if client unregisters
or send request with lesser ab/ib values. Bus driver
will divide bandwidth if interleaving enabled.

Added a macro wrapper to handle negative bw values
since the division utility function can't handle
negative values

CRs-Fixed: 521940
Change-Id: Ic3a216b8efb535593fe02ad3228d71808d2e0f98
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>