MAINTAINERS: Add Felix, Martin, Varshit for mb/amd/onyx

1. Split AMD mainboard between AMD server and AMD non-server SoC
2. Add maintainers for onyx mainboard

Change-Id: I94814da1c06d57cc63c9b968866570a812346fde
Signed-off-by: Varshit Pandya <pandyavarshit@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78987
Reviewed-by: Martin L Roth <gaumless@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index 00dffdd..fba12cc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -136,7 +136,7 @@
 
 
 
-AMD family 17h and 19h reference boards
+AMD non-server family 17h and 19h reference boards
 M:	Felix Held <felix-coreboot@felixheld.de>
 M:	Jason Glenesk <jason.glenesk@gmail.com>
 M:	Fred Reitberger <reitbergerfred@gmail.com>
@@ -149,6 +149,13 @@
 F:	src/mainboard/amd/mandolin/
 F:	src/mainboard/amd/mayan/
 
+AMD server family 19h reference boards
+M:	Felix Held <felix-coreboot@felixheld.de>
+M:	Martin Roth <gaumless@gmail.com>
+M:	Varshit Pandya <pandyavarshit@gmail.com>
+S:	Maintained
+F:	src/mainboard/amd/onyx/
+
 AMD reference boards outside of family 17h and 19h
 S:	Odd Fixes
 L:	amd_coreboot_org_changes@googlegroups.com