MAINTAINERS: update drm/stm drm/sti and cec/sti maintainers

Add Alain as sti maintainer for both drm/sti & cec/sti.
Add Raphaël as stm maintainer for drm/stm.

Signed-off-by: Philippe Cornu <[email protected]>
Reviewed-by: Raphael Gallais-Pou <[email protected]>
Reviewed-by: Alain Volmat <[email protected]>
Link: https://lore.kernel.org/r/[email protected]'
Signed-off-by: Arnd Bergmann <[email protected]>

Author: Philippe Cornu

MAINTAINERS

@@ -6502,6 +6502,7 @@ F:	Documentation/devicetree/bindings/display/rockchip/
 F:	drivers/gpu/drm/rockchip/
 
 DRM DRIVERS FOR STI
+M:	Alain Volmat <[email protected]>
 L:	[email protected]
 S:	Maintained
 T:	git git://anongit.freedesktop.org/drm/drm-misc
@@ -6510,6 +6511,7 @@ F:	drivers/gpu/drm/sti
 
 DRM DRIVERS FOR STM
 M:	Yannick Fertre <[email protected]>
+M:	Raphael Gallais-Pou <[email protected]>
 M:	Philippe Cornu <[email protected]>
 L:	[email protected]
 S:	Maintained
@@ -18439,6 +18441,7 @@ F:	Documentation/devicetree/bindings/sound/st,sti-asoc-card.txt
 F:	sound/soc/sti/
 
 STI CEC DRIVER
+M:	Alain Volmat <[email protected]>
 S:	Maintained
 F:	Documentation/devicetree/bindings/media/stih-cec.txt
 F:	drivers/media/cec/platform/sti/