clocksource/arm_arch_timer: Use arch_timer_read_counter to access stable counters

Instead of always going via arch_counter_get_cntvct_stable to access the
counter workaround, let's have arch_timer_read_counter point to the
right method.

For that, we need to track whether any CPU in the system has a
workaround for the counter. This is done by having an atomic variable
tracking this.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm/include/asm/arch_timer.h

@@ -83,7 +83,7 @@ static inline u32 arch_timer_get_cntfrq(void)
 	return val;
 }
 
-static inline u64 arch_counter_get_cntpct(void)
+static inline u64 __arch_counter_get_cntpct(void)
 {
 	u64 cval;
 
@@ -92,7 +92,12 @@ static inline u64 arch_counter_get_cntpct(void)
 	return cval;
 }
 
-static inline u64 arch_counter_get_cntvct(void)
+static inline u64 __arch_counter_get_cntpct_stable(void)
+{
+	return __arch_counter_get_cntpct();
+}
+
+static inline u64 __arch_counter_get_cntvct(void)
 {
 	u64 cval;
 
@@ -101,6 +106,11 @@ static inline u64 arch_counter_get_cntvct(void)
 	return cval;
 }
 
+static inline u64 __arch_counter_get_cntvct_stable(void)
+{
+	return __arch_counter_get_cntvct();
+}
+
 static inline u32 arch_timer_get_cntkctl(void)
 {
 	u32 cntkctl;