sunxi: pmic_bus: Move SPL I2C addresses into Kconfig

sunxi: pmic_bus: Move SPL I2C addresses into Kconfig

Some of the X-Power AXP PMICs can be ordered with an alternative I2C
address, for instance an AXP717 could be shipped with address 0x34 or
with address 0x35. Similarly the AXP803 lists two possible addresses.
For DM (DT) based drivers this is no problem, but the Allwinner SPL
code relies on exactly one hardcoded address per PMIC so far.

Add a Kconfig variable that holds the I2C address used by the PMIC
accessed in the SPL, and provide the (mostly only one) supported address
as its default, for the PMICs we use. Boards using the other address
can easily set this in their defconfig.
This effectively moves the hardcoding from C code to Kconfig.

That enables to use the AXP717 on some boards with the new Allwinner
A523 chip, which use the other I2C address there.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Heiko Schocher <hs@denx.de>