RK3328 DMC driver needs small (hopefully) update for kernel 5.10

c0rnelius on IRC brought up a compile-time issue on RK3328:

drivers/devfreq/rk3328_dmc.c: In function ‘rk3328_dmcfreq_probe’:
drivers/devfreq/rk3328_dmc.c:751:15: error: too few arguments to function ‘devfreq_event_get_edev_by_phandle’
data->edev = devfreq_event_get_edev_by_phandle(dev, 0);

I found this commit adding a phandle to the prototype of the function: https://github.com/torvalds/linux/commit/02bdbf7d09c059b16047e3d4a05e6d584dd993b6

I only added Piotr since he might be more familiar with the code.