kunit: string-stream-test: Avoid cast warning when testing gfp_t flags

Passing a gfp_t to KUNIT_EXPECT_EQ() causes a cast warning:

lib/kunit/string-stream-test.c:73:9: sparse: sparse: incorrect type in
initializer (different base types) expected long long right_value
got restricted gfp_t const __right

Avoid this by testing stream->gfp for the expected value and passing the
boolean result of this comparison to KUNIT_EXPECT_TRUE(), as was already
done a few lines above in string_stream_managed_init_test().

Signed-off-by: Richard Fitzgerald <[e-mail]>
Fixes: d1a0d699bfc0 ("kunit: string-stream: Add tests for freeing resource-managed string_stream")
Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Reviewed-by: Rae Moar <[e-mail]>
Reviewed-by: David Gow <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

lib/kunit/string-stream-test.c

···
 
 	KUNIT_EXPECT_EQ(test, stream->length, 0);
 	KUNIT_EXPECT_TRUE(test, list_empty(&stream->fragments));
-	KUNIT_EXPECT_EQ(test, stream->gfp, GFP_KERNEL);
+	KUNIT_EXPECT_TRUE(test, (stream->gfp == GFP_KERNEL));
 	KUNIT_EXPECT_FALSE(test, stream->append_newlines);
 
 	KUNIT_EXPECT_TRUE(test, string_stream_is_empty(stream));