ARM: dts: am437x-idk: fix TPS62362 i2c bus

As it turns out, tps62362 is actually on I2C bus0,
not bus1. This has gone unnoticed because Linux
doesn't use (as of now) that regulator at all, it's
setup by the bootloader and left as is.

While at that, also add missing reg property for
our regulator.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>