ARM: dts: am3517-evm: Remove unnessary PMIC parameters

The AM3517-EVM uses a TPS65023 PMIC.  This is already defined
by:  compatible = "ti,tps65023"

There doesn't seem to be a need to have each regulator in the
PMIC with the 'compatible = "regulator-fixed"' since each
regulator has a min and max setting.

Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>