[POWERPC] fix missing #include in sys_ppc32.c

sys_mmap is declared in asm/syscalls.h
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>

arch/powerpc/kernel/sys_ppc32.c

@@ -51,6 +51,7 @@
 #include <asm/time.h>
 #include <asm/mmu_context.h>
 #include <asm/ppc-pci.h>
+#include <asm/syscalls.h>
 
 /* readdir & getdents */
 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char __user *) (de)))