[Refactor RDK-B WiFi HAL]

[Description]
Refactor wifi_getRadioPossibleChannels. Use iwlist to parse possible channel.
Set buffer size as 128 bytes rather than 64 bytes (limit of document).
The reason is that the result of 5GHz possible channel is over than 64 bytes. If we set 64 bytes the result would be cut off by the size limitation.
And the caller, WiFiAgent and TR181, also give 128 bytes to the buffer, so set 128 bytes would cause error.

[Release-log]
N/A

diff --git a/recipes-ccsp/hal/hal-wifi-patches/0027-HAL-refactor-wifi_getRadioPossibleChannels.patch b/recipes-ccsp/hal/hal-wifi-patches/0027-HAL-refactor-wifi_getRadioPossibleChannels.patch
new file mode 100644
index 0000000..cdd9880
--- /dev/null
+++ b/recipes-ccsp/hal/hal-wifi-patches/0027-HAL-refactor-wifi_getRadioPossibleChannels.patch
@@ -0,0 +1,39 @@
+From 312aae9b294a5cb7448887db34654383839a32da Mon Sep 17 00:00:00 2001
+From: "Allen.Ye" <allen.ye@mediatek.com>
+Date: Tue, 24 May 2022 13:53:35 +0800
+Subject: [PATCH] HAL: refactor wifi_getRadioPossibleChannels
+
+---
+ source/wifi/wifi_hal.c | 14 ++++++++++++--
+ 1 file changed, 12 insertions(+), 2 deletions(-)
+
+diff --git a/source/wifi/wifi_hal.c b/source/wifi/wifi_hal.c
+index f15d2c9..a451b30 100644
+--- a/source/wifi/wifi_hal.c
++++ b/source/wifi/wifi_hal.c
+@@ -1571,10 +1571,20 @@ INT wifi_setRadioChannelMode(INT radioIndex, CHAR *channelMode, BOOL gOnlyFlag,
+ //The output_string is a max length 64 octet string that is allocated by the RDKB code.  Implementations must ensure that strings are not longer than this.
+ INT wifi_getRadioPossibleChannels(INT radioIndex, CHAR *output_string)	//RDKB
+ {
++    WIFI_ENTRY_EXIT_DEBUG("Inside %s:%d\n",__func__, __LINE__);
+     if (NULL == output_string) 
+         return RETURN_ERR;
+-    //TODO:read this from iw phy phyX info |grep MHz
+-    snprintf(output_string, 64, (radioIndex == 0)?"1,2,3,4,5,6,7,8,9,10,11":"36,40,44,48,52,56,60,64,100,104,108,112,116,120,124,128,132,136,140");
++
++    char cmd[MAX_CMD_SIZE] = {0};
++    char buf[MAX_BUF_SIZE] = {0};
++
++    // Parse possible channel number and separate them with commas.
++    snprintf(cmd, sizeof(cmd), "iwlist %s%d channel | grep GHz | tr -s ' ' | cut -d ' ' -f3 | tr '\n' ',' | sed 's/.$//'", AP_PREFIX, radioIndex);
++    _syscmd(cmd,buf,sizeof(buf));
++    snprintf(output_string, 128, "%s", buf);
++
++    WIFI_ENTRY_EXIT_DEBUG("Exiting %s:%d\n",__func__, __LINE__);
++    return RETURN_OK;
+ #if 0
+     char IFName[50] ={0};
+     char buf[MAX_BUF_SIZE] = {0};
+-- 
+2.18.0
+