Headset icon: Fix incorrectly sized drawables for MDPI/HDPI

When the original icon was inserted the creator forgot to make it 38x38 (for hdpi) or 25x25 (for mdpi) which meant it got stretched out and therefore both blurry and too big.

Change-Id: I8c5078f4b6406381c3560cbb4c1399a236856eb0