netipmid: Set right value for session->channelNum.

Use getInterfaceIndex() to find the channel number on which
netipmid waits for incoming messages. session->channelNum should
use this value instead of static value 'ipmi::EChannelID::chanLan1'.

Tested-by:
1. Enable SOL payload in channel 3, and disable it in channel 1.
   Verify SOL session establishes in channel 3, and fails in channel 1.
   (session->channelNum is used by 'Set User Payload Access(SOL)).

Signed-off-by: Saravanan Palanisamy <saravanan.palanisamy@linux.intel.com>
Change-Id: If7baecc6a15a327629e10ce6b4cf01ff020b0ee4
diff --git a/command/rakp12.cpp b/command/rakp12.cpp
index 01355d1..2ab9fcd 100644
--- a/command/rakp12.cpp
+++ b/command/rakp12.cpp
@@ -184,8 +184,8 @@
             static_cast<uint8_t>(RAKP_ReturnCode::UNAUTH_NAME);
         return outPayload;
     }
-    // TODO Replace with proper calls.
-    uint8_t chNum = static_cast<uint8_t>(ipmi::EChannelID::chanLan1);
+
+    uint8_t chNum = static_cast<uint8_t>(getInterfaceIndex());
     // Get channel based access information
     if ((ipmi::ipmiUserGetPrivilegeAccess(
              userId, chNum, session->sessionUserPrivAccess) != IPMI_CC_OK) ||