clocksource/drivers/arm_arch_timer: Fix read and iounmap of incorrect variable

Fix boot warning 'Trying to vfree() nonexistent vm area'
from arch_timer_mem_of_init().

Refactored code attempts to read and iounmap using address frame
instead of address ioremap(frame->cntbase).

Fixes: c389d701 ("clocksource: arm_arch_timer: split MMIO timer probing.")
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Reviewed-by: Fu Wei <fu.wei@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/arm_arch_timer.c

@@ -1209,9 +1209,9 @@ arch_timer_mem_frame_get_cntfrq(struct arch_timer_mem_frame *frame)
 		return 0;
 	}
 
-	rate = readl_relaxed(frame + CNTFRQ);
+	rate = readl_relaxed(base + CNTFRQ);
 
-	iounmap(frame);
+	iounmap(base);
 
 	return rate;
 }