Documentation: kernel-parameters: Add RISCV for nohlt

Since commit bcf11b5e ("riscv: Enable idle generic idle loop") enable
idle generic idle loop for RISCV, but the document is not updated
synchronously, so update RISCV support for nohlt.
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Fixes: bcf11b5e ("riscv: Enable idle generic idle loop")
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240604114005.875609-1-ruanjinjie@huawei.com

Documentation/admin-guide/kernel-parameters.txt

@@ -3914,7 +3914,7 @@
 
 	nohibernate	[HIBERNATION] Disable hibernation and resume.
 
-	nohlt		[ARM,ARM64,MICROBLAZE,MIPS,PPC,SH] Forces the kernel to
+	nohlt		[ARM,ARM64,MICROBLAZE,MIPS,PPC,RISCV,SH] Forces the kernel to
 			busy wait in do_idle() and not use the arch_cpu_idle()
 			implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP
 			to be effective. This is useful on platforms where the