MAINTAINERS: Fix PC file pattern

Only one pattern is allowed per F: line, split it in two.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Cc: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index cce37e7..83d3568 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -399,7 +399,8 @@
 PC
 M: Anthony Liguori <aliguori@us.ibm.com>
 S: Supported
-F: hw/pc.[ch] hw/pc_piix.c
+F: hw/pc.[ch]
+F: hw/pc_piix.c
 
 Xtensa Machines
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