drivers: fsa: Fix mute on USB digital hs after SSR

Mute is observed on USB digital headset after SSR due to
headset removal being called. Do not reset switch settings
during fsa unregister to resolve this.

Change-Id: Ia2e349b3913ebfefbf8c19316b2c70b6c314cb92
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>