MAINTAINERS: Fix the PC87312 include path

Missed while moving it in 0d09e41a.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20180308223946.26784-5-f4bug@amsat.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -776,9 +776,10 @@ F: hw/ppc/prep_systemio.c
 F: hw/ppc/rs6000_mc.c
 F: hw/pci-host/prep.[hc]
 F: hw/isa/i82378.c
-F: hw/isa/pc87312.[hc]
+F: hw/isa/pc87312.c
 F: hw/dma/i82374.c
 F: hw/timer/m48t59-isa.c
+F: include/hw/isa/pc87312.h
 F: include/hw/timer/m48t59.h
 F: pc-bios/ppc_rom.bin