ASoC/MFD: twl6040: Combine bit definitions for Headset control registers

Use one set of defines for the HS bits, since they are identical in both
control register.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>