MAINTAINERS: Add entry for STM32 DMA controllers drivers and documentation

Add an entry to make myself a maintainer of STM32 DMA controllers drivers
and documentation.

Signed-off-by: Amelie Delaunay <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

MAINTAINERS

···
 F:	Documentation/devicetree/bindings/sound/st,stm32-*.yaml
 F:	sound/soc/stm/
 
+STM32 DMA DRIVERS
+M:	Amélie Delaunay <[e-mail]>
+L:	[e-mail]
+L:	[e-mail] (moderated for non-subscribers)
+S:	Maintained
+F:	Documentation/arch/arm/stm32/stm32-dma-mdma-chaining.rst
+F:	Documentation/devicetree/bindings/dma/stm32/
+F:	drivers/dma/stm32/
+
 STM32 TIMER/LPTIMER DRIVERS
 M:	Fabrice Gasnier <[e-mail]>
 S:	Maintained