ARM: ux500: delete TPS6105X selection

Having this driver selected here only cause problems, get it
out of there and selected it from menuconfig or wherever
instead. Mea culpa.

Cc: Mathieu Poirer <mathieu.poirier@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>