dm: cleanup assert in core.c

- check input by condition check, instead of assert.
 - remove redundant header file including for some files.

Tracked-On: #3252
Signed-off-by: Yonghua Huang <yonghua.huang@intel.com>
Reviewed-by: Shuo Liu <shuo.a.liu@intel.com>

devicemodel/hw/platform/tpm/tpm.c

@@ -6,7 +6,6 @@
  */
 
 #include <stdlib.h>
-#include <assert.h>
 #include <stdio.h>
 #include <string.h>
 #include <stdbool.h>

devicemodel/hw/platform/tpm/tpm_crb.c

@@ -10,7 +10,6 @@
 #include <stdlib.h>
 #include <stdbool.h>
 #include <string.h>
-#include <assert.h>
 #include <pthread.h>
 
 #include "vmmapi.h"

devicemodel/hw/platform/tpm/tpm_emulator.c

@@ -19,7 +19,6 @@
 #include <stdbool.h>
 #include <sys/stat.h>
 #include <fcntl.h>
-#include <assert.h>
 
 #include "vmmapi.h"
 #include "tpm_internal.h"