disp: msm: Fix byte alignment problem on 32bits OS

There is potential byte alignment problem on 32bits OS which will
cause incorrect histogram blob id getting from the user space.
This change fixes byte alignment problem on 32bits OS by keeping
the struct members in one complete struct as the user space using.

In previous code start address of 'info' would align to multiple of 8,
so there would be 4 bytes padding between member 'event' and 'info'
on 32 bits OS. It is affected by member 'base'. But user space just
uses struct drm_msm_event_resp only, not affected by member 'base'.
Driver code intends to send drm_msm_event_resp, but actually send
unpacked members.

Change-Id: I5410f5b1626387707a57cbcef9c651aa11914d9d
Signed-off-by: Renchao Liu <rencliu@codeaurora.org>