ARM: dts: dra71-evm: mark ldo0 regulator as always on

LDO0 regulator must remain enabled always on dra71-evm boards. Disabling
this violates the data manual and will damage the device over time.

Reported-by: Brad Griffis <bgriffis@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>