dt-bindings: sifive-ccache: change Sifive L2 cache to Composable cache

dt-bindings: sifive-ccache: change Sifive L2 cache to Composable cache

Since composable cache may be L3 cache if private L2 cache exists, we
should use its original name Composable cache to prevent confusion.

Signed-off-by: Zong Li <zong.li@sifive.com>
Suggested-by: Conor Dooley <conor.dooley@microchip.com>
Suggested-by: Ben Dooks <ben.dooks@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220913061817.22564-2-zong.li@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>