Add missing updated MDPI/HDPI icons for Halo

Change-Id: I0299ec08410584751c34a4cafd4ca698fc10ab7e

Conflicts:

	packages/SystemUI/res/drawable-hdpi/halo_back_left.png
	packages/SystemUI/res/drawable-hdpi/halo_back_right.png
	packages/SystemUI/res/drawable-hdpi/halo_bg.png
	packages/SystemUI/res/drawable-hdpi/halo_clear_all.png
	packages/SystemUI/res/drawable-hdpi/halo_dismiss.png
	packages/SystemUI/res/drawable-mdpi/halo_back_left.png
	packages/SystemUI/res/drawable-mdpi/halo_back_right.png
	packages/SystemUI/res/drawable-mdpi/halo_bg.png
	packages/SystemUI/res/drawable-mdpi/halo_clear_all.png
	packages/SystemUI/res/drawable-mdpi/halo_dismiss.png