staging: most: hdm-dim2: remove macro ENABLE_HDM_TEST

This patch removes the macro ENABLE_HDM_TEST, which was needed while
doing DIM2-HAL simulations. But these are not conducted anymore.

Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>