clk: imx: rename video_pll1 to video_pll

[backport from linux commit bedcf9d1dcf88ed38731f0ac9620e5a421e1e9d6]

Unlike audio_pll1 and audio_pll2, there is no video_pll2. Further, the
name used in the RM is video_pll. So, let's rename "video_pll1" to
"video_pll" to be consistent with the RM and avoid misunderstandings.

No functional changes intended.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Acked-by: Sean Anderson <seanga2@gmail.com>
Link: https://lore.kernel.org/r/20221219113127.528282-3-dario.binacchi@amarulasolutions.com