powerpc: include export.h for files using EXPORT_SYMBOL/THIS_MODULE

Fix failures in powerpc associated with the previously allowed
implicit module.h presence that now lead to things like this:

arch/powerpc/mm/mmu_context_hash32.c:76:1: error: type defaults to 'int' in declaration of 'EXPORT_SYMBOL_GPL'
arch/powerpc/mm/tlb_hash32.c:48:1: error: type defaults to 'int' in declaration of 'EXPORT_SYMBOL'
arch/powerpc/kernel/pci_32.c:51:1: error: type defaults to 'int' in declaration of 'EXPORT_SYMBOL_GPL'
arch/powerpc/kernel/iomap.c:36:1: error: type defaults to 'int' in declaration of 'EXPORT_SYMBOL'
arch/powerpc/platforms/44x/canyonlands.c:126:1: error: type defaults to 'int' in declaration of 'EXPORT_SYMBOL'
arch/powerpc/kvm/44x.c:168:59: error: 'THIS_MODULE' undeclared (first use in this function)

[with several contibutions from Stephen Rothwell <sfr@canb.auug.org.au>]

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index d417511..bc4d50d 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -20,6 +20,7 @@
  */
 
 #include <linux/kvm_host.h>
+#include <linux/export.h>
 #include <linux/err.h>
 #include <linux/slab.h>