rtlwifi: Add rate section and its related definition and comment

Add comments to make it to be easier to understand, and add compile time
assertions.
Signed-off-by: NPing-Ke Shih <pkshih@realtek.com>
Acked-by: NLarry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtlwifi/base.c

@@ -2647,6 +2647,9 @@ EXPORT_SYMBOL_GPL(rtl_global_var);
 static int __init rtl_core_module_init(void)
 {
 	BUILD_BUG_ON(TX_PWR_BY_RATE_NUM_RATE < TX_PWR_BY_RATE_NUM_SECTION);
+	BUILD_BUG_ON(MAX_RATE_SECTION_NUM != MAX_RATE_SECTION);
+	BUILD_BUG_ON(MAX_BASE_NUM_IN_PHY_REG_PG_24G != MAX_RATE_SECTION);
+	BUILD_BUG_ON(MAX_BASE_NUM_IN_PHY_REG_PG_5G != (MAX_RATE_SECTION - 1));
 
 	if (rtl_rate_control_register())
 		pr_err("rtl: Unable to register rtl_rc, use default RC !!\n");

drivers/net/wireless/realtek/rtlwifi/wifi.h

@@ -164,7 +164,7 @@ enum rtl8192c_h2c_cmd {
 #define MAX_TX_COUNT			4
 #define MAX_REGULATION_NUM		4
 #define MAX_RF_PATH_NUM			4
-#define MAX_RATE_SECTION_NUM		6
+#define MAX_RATE_SECTION_NUM		6	/* = MAX_RATE_SECTION */
 #define MAX_2_4G_BANDWIDTH_NUM		4
 #define MAX_5G_BANDWIDTH_NUM		4
 #define	MAX_RF_PATH			4
@@ -175,8 +175,8 @@ enum rtl8192c_h2c_cmd {
 #define TX_PWR_BY_RATE_NUM_RF		4
 #define TX_PWR_BY_RATE_NUM_SECTION	12
 #define TX_PWR_BY_RATE_NUM_RATE		84 /* >= TX_PWR_BY_RATE_NUM_SECTION */
-#define MAX_BASE_NUM_IN_PHY_REG_PG_24G  6
-#define MAX_BASE_NUM_IN_PHY_REG_PG_5G	5
+#define MAX_BASE_NUM_IN_PHY_REG_PG_24G	6  /* MAX_RATE_SECTION */
+#define MAX_BASE_NUM_IN_PHY_REG_PG_5G	5  /* MAX_RATE_SECTION -1 */
 
 #define BUFDESC_SEG_NUM		1 /* 0:2 seg, 1: 4 seg, 2: 8 seg */
 
@@ -272,6 +272,7 @@ enum rate_section {
 	HT_MCS8_MCS15,
 	VHT_1SSMCS0_1SSMCS9,
 	VHT_2SSMCS0_2SSMCS9,
+	MAX_RATE_SECTION,
 };
 
 enum intf_type {