media: rockchip: hdmirx: add VIDIOC_G_PARM

[amazingfate]

This will let obs linux-v4l2 plugin show display from hdmirx of rk3588.
OBS code using these API: https://github.com/obsproject/obs-studio/blob/master/plugins/linux-v4l2/v4l2-helpers.c#L244-L254

@ramiropolla @rigaya

[ramiropolla]

I'm not a kernel dev, but after a quick glance and checking how other drivers do it, I see at least two issues:

• hdmirx_g_parm() is not checking for parm->type like other drivers
• if changing parameters is not supported, then we shouldn't implement vidioc_s_parm() (although I see there's a function called hdmirx_s_dv_timings())
• I'm not sure about the readbuffers. where did you get that info?

[amazingfate]

I don't know readbuffers value exactly, it just works. Maybe not returning it will work, I will test.
I will add check for type V4L2_BUF_TYPE_VIDEO_CAPTURE and remove vidioc_s_parm to see if it will work.

[amazingfate]

Add checking parm->type is V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE, remove vidioc_s_parm and return of readbuffers.
Tested on obs with mesa llvmpipe driver, panfork driver failed with gl call error.

[amazingfate]

This commit is not that useful on 5.10 kernel because GPU support is bad. Since we have panthor support on 6.1, I will test with panthor and create a pr for 6.1 kernel.