arm: zynq: don't disable CONFIG_ARM_GLOBAL_TIMER due to CONFIG_CPU_FREQ anymore

Now ARM global timer driver could work even if it's source clock rate
changes, so we don't need to disable that driver when cpu frequency scaling
is in use.

This cause Zynq arch to get support for timer delay and get_cycles().

Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210406130045.15491-3-andrea.merello@gmail.com