[ARM] remove bogus #ifdef CONFIG_HIGHMEM in show_pte()

The restriction on !CONFIG_HIGHMEM is unneeded since page tables are
currently never allocated with highmem pages, and actually disable PTE
dump whenever highmem is configured.  Let's have a dynamic test to better
describe the current limitation instead.
Signed-off-by: NNicolas Pitre <nico@marvell.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/fault.c

@@ -14,6 +14,7 @@
 #include <linux/init.h>
 #include <linux/kprobes.h>
 #include <linux/uaccess.h>
+#include <linux/page-flags.h>
 
 #include <asm/system.h>
 #include <asm/pgtable.h>
@@ -83,13 +84,14 @@ void show_pte(struct mm_struct *mm, unsigned long addr)
 			break;
 		}
 
-#ifndef CONFIG_HIGHMEM
 		/* We must not map this if we have highmem enabled */
+		if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
+			break;
+
 		pte = pte_offset_map(pmd, addr);
 		printk(", *pte=%08lx", pte_val(*pte));
 		printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
 		pte_unmap(pte);
-#endif
 	} while(0);
 
 	printk("\n");