msm: cleanup: union gsi_evt_scratch

Remove __packed from the usage of union gsi_evt_scratch.
__packed is only needed in the union definition.

include/linux/msm_gsi.h:
union __packed gsi_evt_scratch {
    ...
}

Bug: 139442076
Bug: 139808631
Bug: 140528058
Change-Id: If3d0e1bc2674f01d5a9a02e73d33b28a648539bc
Signed-off-by: Petri Gynther <pgynther@google.com>
(cherry picked from commit 33c2fa85bdfd90436d4c975757eefc6706a785c5)