ARM: dts: am33xx: Map baseboard EEPROM on BeagleBone Black

The identification EEPROM on the BeagleBone Black baseboard is supplied
by VDD_3V3A which is supplied by LDO4 on the PMIC. Map this as per the DT
binding for the EEPROM. Since this supply is always-on this has no
practical impact but it does silence a warning at boot due to using a dummy
regulator.

Signed-off-by: Mark Brown <broonie@kernel.org>
Message-Id: <20220620152150.708664-1-broonie@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>