arm64: dts: s32g2: Add the System Timer Module nodes

arm64: dts: s32g2: Add the System Timer Module nodes

The s32g2 has a STM module containing 8 timers. Each timer has a
dedicated interrupt and share the same clock.

Add the timers STM0->STM6 nodes for the s32g2 SoC. The STM7 node is
not added because it is slightly different and needs an extra property
which will be added later when supported by the driver.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Ghennadi Procopciuc <ghennadi.procopciuc@nxp.com>
Cc: Thomas Fossati <thomas.fossati@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>