MAINTAINERS: drop Christoph Egger

Other Amazon folks indicate he's not available as a maintainer anymore
at this point in time. Maintenance of the MCE sub-component will fall
back to the x86 maintainers.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -269,11 +269,6 @@ F:  xen/include/asm-*/livepatch.h
 F:  xen/include/xen/livepatch*
 F:  xen/test/livepatch/*
 
-MACHINE CHECK (MCA) & RAS
-M:	Christoph Egger <chegger@xxxxxxxxx>
-S:	Supported
-F:	xen/arch/x86/cpu/mcheck/
-
 MINI-OS
 M:	Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
 S:	Supported