msm: vidc: Add entry to scale buses for True 4k @ 24 fps

We weren't asking for enough bandwidth for 4k (3840x2160) @ 30 fps
sessions because we were missing an entry for True 4k @ 24 fps (which
requires less bandwith).  Now sessions of the former type are mapped to
the right ab-ib values.

Also get rid of some unused macros in msm_vidc_common.c

Change-Id: I40d3f8d079ffba586d96e8042b40bb0648ba7ae2
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>