unittest: pass_haltests: Remove unreached return statement and unneeded if statement

unittest: pass_haltests: Remove unreached return statement and unneeded if statement

ASSERT_EQ() macro is able to check the 'return value' and then if 'return value'
is less than zero, print error message and exit the unittest. It means that
the separate 'if statement' for checking 'return value' is not neeeded
when using ASSERT_EQ().

Also, when using ASSERT_EQ() macro, the unittest don't need to call
'return statement' because ASSERT_EQ() return right now if 'return value'
is error. So, remove unreached return statement.

Change-Id: I2808d033e669a021a5b53226bf44c91241640c9a
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>