tci: Fix wrong macro name for debug code

tci: Fix wrong macro name for debug code

Code which is compiled with CONFIG_TCG_DEBUG (set by configure option
--enable-debug-tcg) should not disable the assert macro by
defining NDEBUG.

With the wrong macro name CONFIG_TCG_DEBUG, all assertions in tci.c
were completely useless because NDEBUG was always defined.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>