drm/gma500/oaktrail_lvds_i2c: Remove unused variables 'tmp'

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/gma500/oaktrail_lvds_i2c.c: In function ‘get_clock’:
 drivers/gpu/drm/gma500/oaktrail_lvds_i2c.c:69:11: warning: variable ‘tmp’ set but not used [-Wunused-but-set-variable]
 drivers/gpu/drm/gma500/oaktrail_lvds_i2c.c: In function ‘get_data’:
 drivers/gpu/drm/gma500/oaktrail_lvds_i2c.c:83:11: warning: variable ‘tmp’ set but not used [-Wunused-but-set-variable]

Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Jan Safrata <jan.nikitenko@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210115181601.3432599-19-lee.jones@linaro.org