ARM: meson: add meson8 support

Add a MACH_MESON8 symbol and add "amlogic,meson8" to the list of
compatible strings for the Meson DT machine to support devices based
on the Meson8 family of SoCs.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Carlo Caione <carlo@caione.org>
ARM: meson: document meson8 compatible properties

Add device tree bindings documentation for Amlogic Meson8 SoCs.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Carlo Caione <carlo@caione.org>
ARM: meson: enable L2 cache

This enables the L2 cache controller available in Amlogic SoCs.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Carlo Caione <carlo@caione.org>
clocksource: meson6: Select CLKSRC_MMIO

Select CLKSRC_MMIO when the meson6_timer driver is enabled since it
depends on clocksource MMIO functions.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Signed-off-by: Carlo Caione <carlo@caione.org>