BaseTools: change the Division Operator in the expression

PEP 238 -- Changing the Division Operator
x/y to return a reasonable approximation of the mathematical result
    of the division ("true division")
x//y to return the floor ("floor division")

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/AutoGen.py

@@ -3729,7 +3729,7 @@ class ModuleAutoGen(AutoGen):
                         Padding = '0x00, '
                         if Unicode:
                             Padding = Padding * 2
-                            ArraySize = ArraySize / 2
+                            ArraySize = ArraySize // 2
                         if ArraySize < (len(PcdValue) + 1):
                             if Pcd.MaxSizeUserSet:
                                 EdkLogger.error("build", AUTOGEN_ERROR,