meta-phosphor: npcm8xx.bbclass: update padding

Do not add padding size once binary file alreay aligned.

Change-Id: I2c30d86f222f4cfd53a23ac128ad876413978224
Signed-off-by: Brian Ma <chma0@nuvoton.com>
diff --git a/meta-phosphor/classes/image_types_phosphor_nuvoton_npcm8xx.bbclass b/meta-phosphor/classes/image_types_phosphor_nuvoton_npcm8xx.bbclass
index 6ea5389..9b6db79 100644
--- a/meta-phosphor/classes/image_types_phosphor_nuvoton_npcm8xx.bbclass
+++ b/meta-phosphor/classes/image_types_phosphor_nuvoton_npcm8xx.bbclass
@@ -30,10 +30,12 @@
     TIP_IMAGE = d.getVar('TIP_IMAGE', True)
     def Pad_bin_file_inplace(inF, align):
         padding_size = 0
-        padding_size_end = 0
 
         F_size = os.path.getsize(inF)
 
+        if ((F_size % align) == 0):
+            return
+
         padding_size = align - (F_size % align)
 
         infile = open(inF, "ab")