soc: sifive: ccache: determine the cache level from dts

soc: sifive: ccache: determine the cache level from dts

Composable cache could be L2 or L3 cache, use 'cache-level' property of
device node to determine the level.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220913061817.22564-4-zong.li@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>