tci: Fix build regression

tci: Fix build regression

Commit d38ea87ac54af64ef611de434d07c12dc0399216 cleaned the include
statements which resulted in a wrong order of assert.h and the definition
of NDEBUG in tci.c. Normally NDEBUG modifies the definition of the assert
macro, but here this definition comes too late which results in a failing
build.

To fix this, a new macro tci_assert which depends on CONFIG_DEBUG_TCG
is introduced. Only builds with CONFIG_DEBUG_TCG will use assertions.
Even in this case, it is still possible to disable assertions by
defining NDEBUG via compiler settings.

Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>