[ARM] amba drivers: don't pass a consumer clock name for devices with unique clocks

[ARM] amba drivers: don't pass a consumer clock name for devices with unique clocks

Where devices only have one consumer, passing a consumer clock ID
has no real benefit, and it only encourages wrong implementations of
the clk API.  Remove it.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>