msm: msm_bus: Correct bypass mode settings for MM masters

Due to an incorrect perm mode check, the saturation and
bandwidth registers for MM masters are being written to
even though they are in bypass mode.
Correct this by changing the allowed modes and the check
during init.

Change-Id: Ib5a3643ea145d7bf3dae984ebaff9094d919fbea
Signed-off-by: Gagan Mac <gmac@codeaurora.org>