add compare check with dd & diff

add compare check with dd & diff

In case of that there is not available cmp with '-n', dd and diff
compoistion could be useful to compare two file.

diff <(dd bs=1 count=$bufsize if=$1 &>/dev/null) <(dd bs=1
count=$bufsize if=$2 &>/dev/null)

**Self evaluation:**
1. Build test:	 [X]Passed [ ]Failed [ ]Skipped
2. Run test:	 [X]Passed [ ]Failed [ ]Skipped

Signed-off-by: jijoong.moon <jijoong.moon@samsung.com>