Add node to support the QUP6 I2C controller inside
of IPQ8074.
It is exactly the same as QUP2 and QUP3 controllers.

Some routers like Xiaomi AX9000 and Netgear RBK850
use this bus.
Signed-off-by: Robert Marko <robimarko@gmail.com>
Link: https://lore.kernel.org/r/20210619162751.2336974-1-robimarko@gmail.comSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>