ARM: tegra: fix COUNTER_FREQUENCY for T210

While T210 boards all have 38.4MHz crystals, per the TRM, the only
supported configuration is to divide the crystal frequency by 2 to
generate clk_m, which is what feeds the ARM generic timers amongst other
things. Fix the value of COUNTER_FREQUENCY to reflect this divide-by-2.

When I queried the 19.2 value in Tom's original T210 patches, I wasn't
aware of this extra divide-by-2, and didn't notice any effect from the
incorrect value, since its only used if U-Boot is booted in EL3, whereas
I'm booting it in EL2.

Reported-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/include/configs/p2371-2180.h b/include/configs/p2371-2180.h
index 378d5a9..f311ae9 100644
--- a/include/configs/p2371-2180.h
+++ b/include/configs/p2371-2180.h
@@ -60,6 +60,7 @@
 #include "tegra-common-usb-gadget.h"
 #include "tegra-common-post.h"
 
-#define COUNTER_FREQUENCY	38400000
+/* Crystal is 38.4MHz. clk_m runs at half that rate */
+#define COUNTER_FREQUENCY	19200000
 
 #endif /* _P2371_2180_H */