MAINTAINERS: alpine: add a new maintainer and update the entry

Add myself as a co-maintainer for the Alpine support. Also update the
entry to take in account Alpine ARM64 boards, Alpine ARM device trees
and Alpine-specific drivers.

Signed-off-by: Antoine Tenart <[e-mail]>
Acked-by: Tsahee Zidenberg <[e-mail]>
Signed-off-by: Olof Johansson <[e-mail]>

MAINTAINERS

···
 
 ARM/Annapurna Labs ALPINE ARCHITECTURE
 M:	Tsahee Zidenberg <[e-mail]>
+M:	Antoine Tenart <[e-mail]>
 S:	Maintained
 F:	arch/arm/mach-alpine/
+F:	arch/arm/boot/dts/alpine*
+F:	arch/arm64/boot/dts/al/
+F:	drivers/*/*alpine*
 
 ARM/ATMEL AT91RM9200, AT91SAM9 AND SAMA5 SOC SUPPORT
 M:	Nicolas Ferre <[e-mail]>