msm: msm_bus: Changes for QOS computation at BIMC

Modify the computation of dynamic QOS parameters for BIMC. The bandwidth
paramter was incorrectly assumed to be in beats/s, it is infact in bytes/s
so there is no need to take bus width into account.
Also change resolution for statically prgrammed grant period to nano second
from micro second since each tick of the QOS clock is in the nano second
range.

Change-Id: Iad9ebc7837b769f8cd9c4215cb102f6916c0845d
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>