ARM: Avoid evaluating page_address() multiple times

page_address() is a function call rather than a macro, and so:

	if (page_address(page))
		do_something(page_address(page));

results in two calls to this function.  This is unnecessary; remove
the duplication.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/flush.c

@@ -111,6 +111,8 @@ void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
 
 void __flush_dcache_page(struct address_space *mapping, struct page *page)
 {
+	void *addr = page_address(page);
+
 	/*
 	 * Writeback any data associated with the kernel mapping of this
 	 * page.  This ensures that data in the physical page is mutually
@@ -121,9 +123,9 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page)
 	 * kmap_atomic() doesn't set the page virtual address, and
 	 * kunmap_atomic() takes care of cache flushing already.
 	 */
-	if (page_address(page))
+	if (addr)
 #endif
-		__cpuc_flush_dcache_page(page_address(page));
+		__cpuc_flush_dcache_page(addr);
 
 	/*
 	 * If this is a page cache page, and we have an aliasing VIPT cache,