Load libdrm at run time

Remove the compile time dependency on libdrm. Load it at the run
time instead.

Add the headers missed from smi-lib

Change-Id: Ie1ecf293b51425b6a61c502d11a42809dc099f70

amd_smi/example/amd_smi_example.cc

@@ -77,9 +77,9 @@ int main() {
 
   // For each socket, get identifier and devices
   for (uint32_t i=0; i < socket_count; i++) {
-    // Get Socket identifier
+    // Get Socket info
     char socket_name[128];
-    ret = amdsmi_get_socket_identifier(sockets[i], socket_name, 128);
+    ret = amdsmi_get_socket_info(sockets[i], socket_name, 128);
     CHK_AMDSMI_RET(ret)
     std::cout << "Socket " << socket_name << std::endl;