ARM: tegra: avoid using secure carveout RAM

If a secure carveout exists, U-Boot cannot use that memory. Fix
carveout_size() to reflect this, and hence transitively fix
usable_ram_size_below_4g() and board_get_usable_ram_top(). This change
ensures that when U-Boot copies the secure monitor code to install it, the
copy target is not in-use for U-Boot code/data.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/mach-tegra/board2.c

@@ -249,6 +249,10 @@ static ulong carveout_size(void)
 {
 #ifdef CONFIG_ARM64
 	return SZ_512M;
+#elif defined(CONFIG_ARMV7_SECURE_RESERVE_SIZE)
+	// BASE+SIZE might not == 4GB. If so, we want the carveout to cover
+	// from BASE to 4GB, not BASE to BASE+SIZE.
+	return (0 - CONFIG_ARMV7_SECURE_BASE);
 #else
 	return 0;
 #endif