Currently only meson6.dtsi and meson8.dtsi inherit the generic
meson.dtsi. However, since the Meson8b platform is basically a slightly
updated version of Meson8 we can safely inherit meson.dtsi. An indicator
for this are the nodes which are identical in meson.dtsi and
meson8b.dtsi (L2, gic, timer, uart_AO, uart_A, uart_B, uart_C).

Additionally this makes the following devices available on Meson8b which
were not avaialble before (however, since all affected drivers support
Meson6, Meson8 and the whole GX series there's no reason to assume that
they are not working):
- i2c_a and i2c_B
- the IR receiver
- SPFIC (SPI flash controller)
- the dwmac ethernet controller

Differences between Meson8 and Meson8b seem to be:
- ARM Cortex-A5 core instead of Cortex-A9 on Meson8
- dwmac on Meson8b supports RGMII
- small pinctrl updates

Inheriting meson.dtsi makes it easier to maintain by removing duplicate
definitions.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>