dpll: zl3073x: fix memory leak on pin registration failure

dpll: zl3073x: fix memory leak on pin registration failure

If zl3073x_dpll_pin_register() fails, the allocated pin is not yet
added to zldpll->pins list. The error path calls
zl3073x_dpll_pins_unregister() which only iterates pins on the list,
so the current pin is leaked. Free the pin before jumping to the error
label.

Additionally move the pin->dpll_pin = NULL assignment in
zl3073x_dpll_pin_register() from err_register to the common
err_pin_get path. When dpll_pin_get() fails, pin->dpll_pin holds an
ERR_PTR value. Without this fix the subsequent zl3073x_dpll_pin_free()
would trigger a spurious WARN because it checks pin->dpll_pin for
non-NULL.

Fixes: 75a71ecc2412 ("dpll: zl3073x: Register DPLL devices and pins")
Reviewed-by: Petr Oros <poros@redhat.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Link: https://patch.msgid.link/20260519132205.161847-1-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>