lib: utils/timer: Remove Allwinner D1 CLINT compatibles

The allwinner,sun20i-d1-clint compatible string is not documented in any
official binding, so it should not be used by drivers.

The MSWI in the D1 CLINT is compatible with the ACLINT specification, so
it can take advantage of generic driver support. However, that is only
possible if the MSWI and MTIMER are split into separate DT nodes. This
means the final binding for this device is likely to be incompatible
with what is implemented here.

Remove this compatible string from the driver to prevent it from
appearing in a stable version and causing future issues.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Anup Patel <anup@brainfault.org>