phy: rockchip: samsung-hdptx: Set drvdata before enabling runtime PM

In some cases, rk_hdptx_phy_runtime_resume() may be invoked before
platform_set_drvdata() is executed in ->probe(), leading to a NULL
pointer dereference when using the return of dev_get_drvdata().

Ensure platform_set_drvdata() is called before devm_pm_runtime_enable().

Reported-by: Dmitrii Osipenko <dmitry.osipenko@collabora.com>
Fixes: 553be283 ("phy: rockchip: Add Samsung HDMI/eDP Combo PHY driver")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>