drm/ssd130x: remove redundant initialization of pointer mode

Pointer mode is being assigned a value that is never read, it is
being re-assigned later with a new value. The initialization is
redundant and can be removed.

Cleans up clang scan build warning:
drivers/gpu/drm/solomon/ssd130x.c:582:27: warning: Value stored
to 'mode' during its initialization is never read [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220302175309.1098827-1-colin.i.king@gmail.com