This patch adds support to differentiate between `long` and `long long`
format specifiers in tf_printf(). In AArch64, they are the same which is
a 64-bit word. But, in AArch32 they are different and tf_printf() needs
to handle these format specifiers separately. This patch also fixes the
type of variables used to generic C types.

Change-Id: If3bbb0245cd0183acbe13bc1fe0d9743f417578f