rockchip: rv1108: Remove unneeded local rv1108-cru.h

After the conversion of RV1108 to OF_UPSTREAM,
include/dt-bindings/clock/rv1108-cru.h is no longer needed because
there is dts/upstream/include/dt-bindings/clock/rv1108-cru.h from
upstream Linux.

Remove the unneeded rv1108-cru.h file.

Reported-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>