clk: sunxi: Limit legacy clocks to 32-bit ARM

The sunxi legacy clocks were never compatible with any 64-bit SoC,
so there is no point in building them as part of a 64-bit ARM kernel.
They make even less sense being built in to a 64-bit RISC-V kernel.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20220702190135.51744-1-samuel@sholland.org