lib: kunit: Fix compilation test when using TEST_BIT_FIELD_COMPILE

A build condition was missing around a compilation test, this compilation
test comes from the original test_bitfield code.

And removed unnecessary code for this test.

Fixes: d2585f5164 ("lib: kunit: add bitfield test conversion to KUnit")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Vitor Massaru Iha <vitor@massaru.org>
Link: https://lore.kernel.org/linux-next/20201015163056.56fcc835@canb.auug.org.au/
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

lib/bitfield_kunit.c

@@ -125,7 +125,7 @@ static void __init test_bitfields_variables(struct kunit *context)
 	CHECK(u64, 0x0000001f8000000ull);
 }
 
-
+#ifdef TEST_BITFIELD_COMPILE
 static void __init test_bitfields_compile(struct kunit *context)
 {
 	/* these should fail compilation */
@@ -135,13 +135,11 @@ static void __init test_bitfields_compile(struct kunit *context)
 	/* this should at least give a warning */
 	u16_encode_bits(0, 0x60000);
 }
+#endif
 
 static struct kunit_case __refdata bitfields_test_cases[] = {
 	KUNIT_CASE(test_bitfields_constants),
 	KUNIT_CASE(test_bitfields_variables),
-#ifdef TEST_BITFIELD_COMPILE
-	KUNIT_CASE(test_bitfields_compile),
-#endif
 	{}
 };