msm: cleanup: union gsi_wdi_channel_scratch3_reg

Remove __packed from the usage of union gsi_wdi_channel_scratch3_reg.
__packed is only needed in the union definition.

include/linux/msm_gsi.h:
union __packed gsi_wdi_channel_scratch3_reg {
    ...
}

Bug: 139442076
Bug: 139808631
Bug: 140528058
Change-Id: I70edc50fbbe4c004309f76c020ac4d77cad91aad
Signed-off-by: Petri Gynther <pgynther@google.com>
(cherry picked from commit 2871c785dd89dd0926d12a93161fca6e27a6cd2e)