ARM: tegra: enable STDIO deregistration

At the very least when USB keyboard support is enabled, we need to enable
CONFIG_SYS_STDIO_DEREGISTER, so the "usb reset" is able to re-scan USB
ports and find new devices. Enable it everywhere per request from Simon
Glass.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

include/configs/tegra-common.h

@@ -89,6 +89,9 @@
 
 #define CONFIG_CONSOLE_MUX
 #define CONFIG_SYS_CONSOLE_IS_IN_ENV
+#ifndef CONFIG_SPL_BUILD
+#define CONFIG_SYS_STDIO_DEREGISTER
+#endif
 
 /*
  * Miscellaneous configurable options