docs/system: riscv: Fix CLINT name in the sifive_u doc

It's Core *Local* Interruptor, not 'Level'.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210627142816.19789-1-bmeng.cn@gmail.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

docs/system/riscv/sifive_u.rst

@@ -11,7 +11,7 @@ The ``sifive_u`` machine supports the following devices:
 
 * 1 E51 / E31 core
 * Up to 4 U54 / U34 cores
-* Core Level Interruptor (CLINT)
+* Core Local Interruptor (CLINT)
 * Platform-Level Interrupt Controller (PLIC)
 * Power, Reset, Clock, Interrupt (PRCI)
 * L2 Loosely Integrated Memory (L2-LIM)