ipq806x: gcc: add support for child probe

Add support for child probing needed for tsens driver that share the
same regs of gcc for this platform.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Link: https://lore.kernel.org/r/20200716022817.30439-2-ansuelsmth@gmail.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>