powerpc/machdep: Drop include of seq_file.h

Drop the include of seq_file.h in machdep.h, replace it with a forward
declaration of struct seq_file, which is all that's required.

Add direct includes of seq_file.h to some files that were getting
seq_file.h via machdep.h.

Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

arch/powerpc/include/asm/machdep.h

···
 #ifdef __KERNEL__
 
 #include <linux/compiler.h>
-#include <linux/seq_file.h>
 #include <linux/init.h>
 #include <linux/dma-mapping.h>
 #include <linux/export.h>
···
 struct pci_controller;
 struct kimage;
 struct pci_host_bridge;
+struct seq_file;
 
 struct machdep_calls {
 	const char	*name;

arch/powerpc/platforms/52xx/efika.c

···
 #include <generated/utsrelease.h>
 #include <linux/pci.h>
 #include <linux/of.h>
+#include <linux/seq_file.h>
 #include <asm/dma.h>
 #include <asm/time.h>
 #include <asm/machdep.h>

arch/powerpc/platforms/embedded6xx/linkstation.c

···
 #include <linux/kernel.h>
 #include <linux/initrd.h>
 #include <linux/of_platform.h>
+#include <linux/seq_file.h>
 
 #include <asm/time.h>
 #include <asm/mpic.h>

arch/powerpc/platforms/embedded6xx/mvme5100.c

···
 
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
+#include <linux/seq_file.h>
 
 #include <asm/i8259.h>
 #include <asm/pci-bridge.h>

arch/powerpc/platforms/pseries/lpar.c

···
 #include <linux/export.h>
 #include <linux/jump_label.h>
 #include <linux/delay.h>
+#include <linux/seq_file.h>
 #include <linux/stop_machine.h>
 #include <linux/spinlock.h>
 #include <linux/cpuhotplug.h>

arch/powerpc/platforms/pseries/msi.c

···
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/msi.h>
+#include <linux/seq_file.h>
 
 #include <asm/rtas.h>
 #include <asm/hw_irq.h>

arch/powerpc/platforms/pseries/papr_scm.c

···
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/ioport.h>
+#include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/ndctl.h>
 #include <linux/sched.h>

arch/powerpc/sysdev/xive/spapr.c

···
 
 #include <linux/types.h>
 #include <linux/irq.h>
+#include <linux/seq_file.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>