Add fix for GetChannelPaylodSupport

Currently `getChannelName` throws when the channel number
is invalid.
Because of which the error reported is Unspecified.

Example:
root@gb200nvl-obmc:~# ipmitool raw 0x06 0x4E 0x4
[1] Unable to send RAW command (channel=0x0 netfn=0x6 lun=0x0 cmd=0x4e rsp=0xff): Unspecified error

Added a patch to handle this gracefully

Tested:
Tested on gb200nvl-obmc platform
root@gb200nvl-obmc:~# ipmitool raw 0x06 0x4E 0x4
[2] Unable to send RAW command (channel=0x0 netfn=0x6 lun=0x0 cmd=0x4e rsp=0xcc): Invalid data field in request

Change-Id: Ibc9981d5e7143311f28bb9191fed4d68cd81356b
Signed-off-by: Prithvi Pai <ppai@nvidia.com>
diff --git a/transporthandler.cpp b/transporthandler.cpp
index c9a7492..d99c754 100644
--- a/transporthandler.cpp
+++ b/transporthandler.cpp
@@ -1420,8 +1420,16 @@
         return responseInvalidFieldRequest();
     }
 
+    auto channelName = ipmi::getChannelName(channel);
+    if (channelName.empty())
+    {
+        lg2::error("Channel name does not exist for channel {CHANNEL}",
+                   "CHANNEL", channel);
+        return responseInvalidFieldRequest();
+    }
+
     std::string solService{};
-    std::string solPathWitheEthName = solPath + ipmi::getChannelName(channel);
+    std::string solPathWitheEthName = solPath + channelName;
 
     if (ipmi::getService(ctx, solInterface, solPathWitheEthName, solService))
     {
@@ -1597,8 +1605,16 @@
         return responseInvalidFieldRequest();
     }
 
+    auto channelName = ipmi::getChannelName(channel);
+    if (channelName.empty())
+    {
+        lg2::error("Channel name does not exist for channel {CHANNEL}",
+                   "CHANNEL", channel);
+        return responseInvalidFieldRequest();
+    }
+
     std::string solService{};
-    std::string solPathWitheEthName = solPath + ipmi::getChannelName(channel);
+    std::string solPathWitheEthName = solPath + channelName;
 
     if (ipmi::getService(ctx, solInterface, solPathWitheEthName, solService))
     {