Keyguard slice views - fix alignment

Some icons use slight insets by default, which causes alignment issues
with left/right aligned keyguard slice content. Access the wrapped
drawable to remove the inset.

Fixes: 175953174
Test: manual (go/hsv to check alignment)
Change-Id: Iaf5115d771e7aa6bf4f8f6a7434d0a2a0d05da21