[PATCH] sparc: fix header problem in sparc32 build

[Randy Dunlap]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

Add a "struct page;" "stub" to fix a build error in sparc32.
Fixes this error:

../include/linux/highmem.h: In function 'clear_user_highpage':
../include/linux/highmem.h:137:31: error: passing argument 1 of 'sparc_flush_page_to_ram' from incompatible pointer type [-Werror=incompatible-pointer-types]
  clear_user_page(addr, vaddr, page);
                               ^~~~
../arch/sparc/include/asm/page_32.h:24:27: note: in definition of macro 'clear_user_page'
   sparc_flush_page_to_ram(page); \
                           ^~~~

Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
---
 arch/sparc/include/asm/cacheflush_32.h |    1 +
 1 file changed, 1 insertion(+)

--- linux-next-20180717.orig/arch/sparc/include/asm/cacheflush_32.h
+++ linux-next-20180717/arch/sparc/include/asm/cacheflush_32.h
@@ -37,6 +37,7 @@
 #define flush_page_for_dma(addr) \
 	sparc32_cachetlb_ops->page_for_dma(addr)
 
+struct page;
 void sparc_flush_page_to_ram(struct page *page);
 
 #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1