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

arch/arm/mach-zynq/Kconfig

@@ -6,7 +6,7 @@ config ARCH_ZYNQ
 	select ARCH_SUPPORTS_BIG_ENDIAN
 	select ARM_AMBA
 	select ARM_GIC
-	select ARM_GLOBAL_TIMER if !CPU_FREQ
+	select ARM_GLOBAL_TIMER
 	select CADENCE_TTC_TIMER
 	select HAVE_ARM_SCU if SMP
 	select HAVE_ARM_TWD if SMP

drivers/clocksource/Kconfig

@@ -360,6 +360,7 @@ config ARM_GLOBAL_TIMER
 
 config ARM_GT_INITIAL_PRESCALER_VAL
 	int "ARM global timer initial prescaler value"
+	default 2 if ARCH_ZYNQ
 	default 1
 	depends on ARM_GLOBAL_TIMER
 	help