board: st: stm32f746-disco: Update MAINTAINERS file

Vikas has left STMicroelectronics several years ago.
Put myself as maintainer of stm32f746-disco board.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/board/st/stm32f746-disco/MAINTAINERS b/board/st/stm32f746-disco/MAINTAINERS
index 18e4c99..f9c3af6 100644
--- a/board/st/stm32f746-disco/MAINTAINERS
+++ b/board/st/stm32f746-disco/MAINTAINERS
@@ -1,5 +1,5 @@
 STM32F746 DISCOVERY BOARD
-M:	Vikas Manocha <vikas.manocha@st.com>
+M:	Patrice Chotard <patrice.chotard@foss.st.com>
 S:	Maintained
 F:	doc/board/st/
 F:	board/st/stm32f746-disco