nvidia-settings: fix -Werror=format-security errors

Signed-off-by: Sachin Chitte <schitte@nvidia.com>
(cherry picked from commit 2e80e4fdc20e051090289e4b32d713a7c4f7e14c)

Conflicts:
	src/gtk+-2.x/ctkdisplayconfig-utils.c
	src/gtk+-2.x/ctkdisplayconfig.c
319.60
nvidia-settings: fix three -Wformat-security fixes that were missed in the 319.60 tarball

Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Reviewed-by: Daniel Dadap <ddadap@nvidia.com>