dt-bindings: clock: convert bcm2835-aux-clock to yaml

Convert the DT binding document for BCM2835 auxiliary peripheral clock
from .txt to YAML.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/20250503080949.3945-1-wahrenst@gmx.net


Acked-by: Conor Dooley <conor.dooley@microchip.com>
[sboyd@kernel.org: Drop aux label]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>