ARM: dts: am335x-bone-common: Add vcc-supply for on-board eeprom

The on-board eeprom on beaglebone series has a power supply from
VDD_3V3A, add that to dts to reduce dummy regulator warning.

Signed-off-by: Shengyu Qu <wiagn233@outlook.com>
Message-ID: <TY3P286MB2611CDC84604B11570B4A8D2980FA@TY3P286MB2611.JPNP286.PROD.OUTLOOK.COM>
Signed-off-by: Tony Lindgren <tony@atomide.com>