get_maintainers.pl does not handle parenthesis in maintenance areas well
in connection with list emails (here: qemu-ppc@nongnu.org).

Resolve a recurring CC issue breaking git-send-email by reverting part
of commit 085eb217 ("Add David Gibson
for sPAPR in MAINTAINERS file").

Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NAndreas Färber <afaerber@suse.de>