net: allow rps/rfs related configs to be switched

After John Sperbeck reported a compile error if the CONFIG_RFS_ACCEL
is off, I found that I cannot easily enable/disable the config
because of lack of the prompt when using 'make menuconfig'. Therefore,
I decided to change rps/rfc related configs altogether.
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Link: https://lore.kernel.org/r/20240605022932.33703-1-kerneljasonxing@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

net/Kconfig

@@ -290,15 +290,21 @@ config MAX_SKB_FRAGS
 	  If unsure, say 17.
 
 config RPS
-	bool
+	bool "Receive packet steering"
 	depends on SMP && SYSFS
 	default y
+	help
+	  Software receive side packet steering (RPS) distributes the
+	  load of received packet processing across multiple CPUs.
 
 config RFS_ACCEL
-	bool
+	bool "Hardware acceleration of RFS"
 	depends on RPS
 	select CPU_RMAP
 	default y
+	help
+	  Allowing drivers for multiqueue hardware with flow filter tables to
+	  accelerate RFS.
 
 config SOCK_RX_QUEUE_MAPPING
 	bool
@@ -351,7 +357,7 @@ config BPF_STREAM_PARSER
 	  BPF_MAP_TYPE_SOCKMAP.
 
 config NET_FLOW_LIMIT
-	bool
+	bool "Net flow limit"
 	depends on RPS
 	default y
 	help