iio: adc: rzg2l_adc: Set driver data before enabling runtime PM

iio: adc: rzg2l_adc: Set driver data before enabling runtime PM

When stress-testing the system by repeatedly unbinding and binding the ADC
device in a loop, and the ADC is a supplier for another device (e.g., a
thermal hardware block that reads temperature through the ADC), it may
happen that the ADC device is runtime-resumed immediately after runtime PM
is enabled, triggered by its consumer. At this point, since drvdata is not
yet set and the driver's runtime PM callbacks rely on it, a crash can
occur. To avoid this, set drvdata just after it was allocated.

Fixes: 89ee8174e8c8 ("iio: adc: rzg2l_adc: Simplify the runtime PM code")
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://patch.msgid.link/20250810123328.800104-3-claudiu.beznea.uj@bp.renesas.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>