tests: i2c_ram: Fix assert message

Being pedantic, the second parameter to zassert_ok() is supposed to be
a literal format specifier string. (Just as for printf()). Not
directly a variable string to be printed. Let's fix it.

Fixes this build warning:
`warning: format not a string literal and no format arguments`

Signed-off-by: Alberto Escolar Piedras <[email protected]>

Author: aescolar

tests/drivers/i2c/i2c_ram/src/test_i2c_ram.c

@@ -202,7 +202,7 @@ static void check_completion(struct rtio_cqe *cqe, const char *msg)
 	result = cqe->result;
 	rtio_cqe_release(&i2c_rtio, cqe);
 	if (result) {
-		zassert_ok(result, msg);
+		zassert_ok(result, "%s", msg);
 	}
 }