BaseTools: Handle the bytes and str difference

Deal with bytes and str is different, remove the unicode()
Using utcfromtimestamp instead of fromtimestamp.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yunhua Feng <yunhuax.feng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/AutoGen/StrGather.py

@@ -122,6 +122,8 @@ def DecToHexList(Dec, Digit = 8):
 # @retval:       A list for formatted hex string
 #
 def AscToHexList(Ascii):
+    if isinstance(Ascii, bytes):
+        return ['0x{0:02X}'.format(Item) for Item in Ascii]
     return ['0x{0:02X}'.format(ord(Item)) for Item in Ascii]
 
 ## Create content of .h file