sandbox: Fix DT compiler address warnings in sandbox DTs

sandbox: Fix DT compiler address warnings in sandbox DTs

Trivially fix the following warnings in sandbox DTs, which show up with
DTC 1.7.2. Fill in the missing address and adjust emulated I2C address
to fit the 7bit address limit:

"
arch/sandbox/dts/sandbox.dtsi:138.30-140.5: Warning (i2c_bus_reg): /i2c@0/sandbox_pmic: I2C bus unit address format error, expected "40"
arch/sandbox/dts/sandbox.dtsi:146.18-161.5: Warning (i2c_bus_reg): /i2c@0/emul: I2C bus unit address format error, expected "ff"
arch/sandbox/dts/sandbox.dtsi:148.4-17: Warning (i2c_bus_reg): /i2c@0/emul:reg: I2C address must be less than 7-bits, got "0xff". Set I2C_TEN_BIT_ADDRESS for 10 bit addresses or fix the property
"

"
arch/sandbox/dts/.test.dtb.pre.tmp:912.18-926.5: Warning (i2c_bus_reg): /i2c@0/emul: I2C bus unit address format error, expected "ff"
arch/sandbox/dts/.test.dtb.pre.tmp:913.4-17: Warning (i2c_bus_reg): /i2c@0/emul:reg: I2C address must be less than 7-bits, got "0xff". Set I2C_TEN_BIT_ADDRESS for 10 bit addresses or fix the property
arch/sandbox/dts/.test.dtb.pre.tmp:928.30-931.5: Warning (i2c_bus_reg): /i2c@0/sandbox_pmic: I2C bus unit address format error, expected "40"
"

Fix up pmic test to match.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Heiko Schocher <hs@nabladev.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>