docs(maintainers): add missing header files

Few header files are added to the lists tracking code owners of
various modules in TF-A project.

Also remove drivers/nuvoton directory, which does not exist, from the list
of files maintained by the corresponding owners.

Change-Id: Iad7ce5b1430965237004c9e76e972a3469d20c9d
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>

docs/about/maintainers.rst

@@ -234,12 +234,14 @@ Power State Coordination Interface (PSCI)
 :|M|: Lauren Wehrmeister <Lauren.Wehrmeister@arm.com>
 :|G|: `laurenw-arm`_
 :|F|: lib/psci/
+:|F|: include/lib/psci/
 
 DebugFS
 ^^^^^^^
 :|M|: Olivier Deprez <olivier.deprez@arm.com>
 :|G|: `odeprez`_
 :|F|: lib/debugfs/
+:|F|: include/lib/debugfs.h
 
 Firmware Configuration Framework (FCONF)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -250,6 +252,10 @@ Firmware Configuration Framework (FCONF)
 :|M|: Lauren Wehrmeister <Lauren.Wehrmeister@arm.com>
 :|G|: `laurenw-arm`_
 :|F|: lib/fconf/
+:|F|: plat/arm/common/fconf/
+:|F|: include/lib/fconf/
+:|F|: include/plat/arm/common/arm_fconf\_\*
+:|F|: include/plat/arm/common/fconf\_\*
 
 Performance Measurement Framework (PMF)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -271,6 +277,7 @@ Arm CPU libraries
 :|M|: Lauren Wehrmeister <Lauren.Wehrmeister@arm.com>
 :|G|: `laurenw-arm`_
 :|F|: lib/cpus/
+:|F|: include/lib/cpus/
 
 Reliability Availability Serviceabilty (RAS) framework
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -398,6 +405,8 @@ DRTM
 :|M|: Manish Pandey <manish.pandey2@arm.com>
 :|G|: `manish-pandey-arm`_
 :|F|: services/std_svc/drtm
+:|F|: include/plat/common/plat_drtm.h
+:|F|: include/services/drtm_svc.h
 
 PSA Firmware Update
 ^^^^^^^^^^^^^^^^^^^
@@ -636,7 +645,6 @@ Nuvoton npcm845x platform port
 :|M|: Avi Fishman <avi.fishman@nuvoton.com>
 :|G|: `avifishman`_
 :|F|: docs/plat/npcm845x.rst
-:|F|: drivers/nuvoton/
 :|F|: include/drivers/nuvoton/
 :|F|: include/plat/nuvoton/
 :|F|: plat/nuvoton/