Add support to mux in the second external bus interface as
follows:

- CS1 and CS2 on GPIO39 and GPIO40 as func 2
- ADDR_7 thru ADDR_0 on GPIO123 thru GPIO130 as func 1
- CS4, CS3 and CS0 on GPIO132, GPIO133, GPIO134 as func 1
- DATA_15 thru DATA_0 on GPIO135 thru GPIO150 as func 1
- OE on GPIO151 as func 1
- ADV on GPIO153 as func 1
- WE on GPIO157 as func 1

This external bus is used on the APQ8060 Dragonboard to connect
an external SMSC9211 ethernet adapter, but there are many other
usecases for the EBI2.

Cc: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Björn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>