Almost certainly any sane board has the twl4030 has the I2C4
pins connected as those are needed for voltage control during
idle. If the I2C4 lines are not properly muxed, any voltage
scaling over I2C4 will fail.

Let's mux those pins by default, the boards that are not using
them can still configure things separately.

Cc: Kevin Hilman <khilman@linaro.org>
Cc: Nishanth Menon <nm@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>