i2c: qcom-geni: Fix runtime PM mismatch with child devices

We need to enable runtime PM on this i2c controller before populating
child devices with i2c_add_adapter(). Otherwise, if a child device uses
runtime PM and stays runtime PM enabled we'll get the following warning
at boot.

 Enabling runtime PM for inactive device (a98000.i2c) with active children

[...]

 Call trace:
  pm_runtime_enable+0xd8/0xf8
  geni_i2c_probe+0x440/0x460
  platform_drv_probe+0x74/0xc8
[...]

Let's move the runtime PM enabling and setup to before we add the
adapter, so that this device can respond to runtime PM requests from
children.

Fixes: 37692de5 ("i2c: i2c-qcom-geni: Add bus driver for the Qualcomm GENI I2C controller")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>