ARM: ux500: Stop informing the regulator subsystem that we have full constraints

The regulator_has_full_constraints() call is not required if we
are booting with Device Tree as it's assumed in this case.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>