selftests/resctrl: Add resctrl.h into build deps

Makefile only lists *.c as build dependencies for the resctrl_tests
executable which excludes resctrl.h.

Add *.h to wildcard() to include resctrl.h.

Fixes: 591a6e85

 ("selftests/resctrl: Add basic resctrl file system operations and data")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan (Fujitsu) <tan.shaopeng@fujitsu.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>