MFC r356276, r356609-r356610, r356637, r356798-r356800, r356802

r356276:
arm: allwinner: aw_spi: Call bus_generic_attach

This is needed when the driver is compiled into the kernel.
When compiled as a module this will be called from another
code path as we also depend on ofw_spibus.

r356609:
twsi: Rework how we handle the i2c messages

We use to handle each message separately in i2c_transfer but that cannot
work with message with NOSTOP as it confuses the controller that we disable
the interrupts and start a new message.
Handle every message in the interrupt handler and fire a new start condition
if the previous message have NOSTOP, the controller understand this as a
repeated start.
This fixes booting on Allwinner A10/A20 platform where before the i2c controller
used to write 0 to the PMIC register that control the regulators as it though that
this was the continuation of the write message.

Tested on: A20 BananaPi, Cubieboard 1 (kevans)
Reported by: kevans

r356610:
arm: allwinner: axp209: Add regnode_status method

This allow consumers to check if the regulator is enable or not.

r356637:
arm64: allwinner: dtso: Add spi0 spigen DTSO

This overlays can be used on A64 board to use spigen and spi(8)
on the spi0 pins.

Tested On: Pine64-LTS, A64-Olinuxino

Submitted by: Gary Otten <gdotten@gmail.com>

r356798:
axp8xx: Add missing voltage regulators offset

This lead to writing the desired voltage value to the wrong register.

r356799:
axp8xx: Add a regnode_init method

This method will set the desired voltaged based on values in the DTS.
It will not enable the regulator, this is the job of either a consumer
or regnode_set_constraint SYSINIT if the regulator is boot_on or always_on.

r356800:
arm: allwinner: Add support for bank supply

Each GPIO bank is powered by a different pin and so can be powered at different
voltage from different regulators.
Add a new config that now hold the pinmux data and the banks available on each
SoCs.
Since the aw_gpio driver being also the pinmux one it's attached before the PMIC
so add a config_intrhook_oneshot function that will enable the needed regulators
when the system is fully functional.

r356802:
arm: allwinner: ahci: target-supply is optional

The target-supply regulator is optional so don't fail if it's not present.
While here disable the clock on detach.

X-MFC-With: 356600