Wifi-HAL: Fix incorrect firmware log entry

The commit "Add the fw diag msg hdr" introduced an error
while calculating the offset to the next buffer. This
caused incorrect firmware log entries in the ring buffer.

Change-Id: Iccce94c33a41f62f4e7c3477f603a6c8d33a1efa
CRs-Fixed: 913224
Bug: 24350330
diff --git a/qcwcn/wifi_hal/wifilogger_diag.cpp b/qcwcn/wifi_hal/wifilogger_diag.cpp
index 17443cf..742bc98 100644
--- a/qcwcn/wifi_hal/wifilogger_diag.cpp
+++ b/qcwcn/wifi_hal/wifilogger_diag.cpp
@@ -904,10 +904,9 @@
             case WLAN_DIAG_TYPE_MSG:
             {
                 /* Length field is only one byte for WLAN_DIAG_TYPE_MSG */
-                payloadlen = diag_msg_hdr->u.msg_hdr.payload_len +
-                             sizeof(fw_diag_msg_hdr_t);
+                payloadlen = diag_msg_hdr->u.msg_hdr.payload_len;
                 process_firmware_prints(info, (u8 *)diag_msg_hdr,
-                                        payloadlen);
+                                       payloadlen + sizeof(fw_diag_msg_hdr_t));
             }
             break;
             default: