Input: twl6040: Simplify vibra regsiter definitions

The bits within the two control registers (for left and right channel)
are identical.
Use common names for the bits acros the two register.
Also add the missing definition for the path selection bit.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>