The sp804 clocks may be specified in DT, but the kernel may still be using
legacy clocks. This is handled if a single clock for sp804 is present,
but not when 3 clocks are present.

This prevents Versatile platforms from breaking when the DT has clocks
added.
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>