dpll: zl3073x: Include current frequency in supported frequencies list

dpll: zl3073x: Include current frequency in supported frequencies list

Ensure the current pin frequency is always present in the list of
supported frequencies reported to userspace. Previously, if the
firmware node was missing or didn't include the current operating
frequency in the supported-frequencies-hz property, the pin would
report a frequency that wasn't in its supported list.

Get the current frequency early in zl3073x_pin_props_get():
- For input pins: use zl3073x_dev_ref_freq_get()
- For output pins: use zl3073x_dev_output_pin_freq_get()

Place the current frequency at index 0 of the supported frequencies
array, then append frequencies from the firmware node (if present),
skipping any duplicate of the current frequency.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Link: https://patch.msgid.link/20260205154350.3180465-3-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>