selftests/resctrl: Fix feature checks

The MBA and CMT tests expect support of other features to be able to
run.

When platform only supports MBA but not MBM, MBA test will fail with:
Failed to open total bw file: No such file or directory

When platform only supports CMT but not CAT, CMT test will fail with:
Failed to open bit mask file '/sys/fs/resctrl/info/L3/cbm_mask': No such file or directory

It leads to the test reporting test fail (even if no test was run at
all).

Extend feature checks to cover these two conditions to show these tests
were skipped rather than failed.

Fixes: ee041568

 ("selftests/resctrl: Use resctrl/info for feature detection")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Cc: <stable@vger.kernel.org> # selftests/resctrl: Refactor feature check to use resource and feature name
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>