drivers/staging/android: don't use modular references in sync_debug.c

In commit 8a004484 ("staging/android:
create a 'sync' dir for debugfs information"), modular references were
introduced to this file.  However if we look, we find:

drivers/staging/android/Makefile:obj-$(CONFIG_SYNC) += sync.o sync_debug.o

drivers/staging/android/Kconfig:config SYNC
drivers/staging/android/Kconfig:        bool "Synchronization framework"

This file isn't currently buildable as a module, and hence the code
for module_exit is just dead code.  Remove it and the module.h include.

Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>