The alt_ref is present only in Versal-net devices.
Other versal devices do not have it. So remove alt_ref
for versal.

Fixes: 35254680 ("dt-bindings: clock: Add bindings for versal clock driver")
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>

Link: https://lore.kernel.org/r/20231128104348.16372-1-shubhrajyoti.datta@amd.comAcked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>