gpu: drm: gma500: remove two more dead variable

The dead code removal left two unused variables:

drivers/gpu/drm/gma500/mdfld_tpo_vid.c: In function 'tpo_vid_get_config_mode':
drivers/gpu/drm/gma500/mdfld_tpo_vid.c:34:31: error: unused variable 'ti' [-Werror=unused-variable]

This removes them as well.

Fixes: 94d7fb49 ("gpu: drm: gma500: remove dead code")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170522203031.2912874-1-arnd@arndb.de