arch/m68k: Merge variants of fb_pgprotect() into single function

Merge all variants of fb_pgprotect() into a single function body.
There are two different cases for MMU systems. For non-MMU systems,
the function body will be empty. No functional changes, but this
will help with the switch to <asm-generic/fb.h>.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Helge Deller <deller@gmx.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230417125651.25126-8-tzimmermann@suse.de

arch/m68k/include/asm/fb.h

@@ -7,17 +7,13 @@
 #include <asm/page.h>
 #include <asm/setup.h>
 
-#ifdef CONFIG_MMU
-#ifdef CONFIG_SUN3
 static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
 				unsigned long off)
 {
+#ifdef CONFIG_MMU
+#ifdef CONFIG_SUN3
 	pgprot_val(vma->vm_page_prot) |= SUN3_PAGE_NOCACHE;
-}
 #else
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
-{
 	if (CPU_IS_020_OR_030)
 		pgprot_val(vma->vm_page_prot) |= _PAGE_NOCACHE030;
 	if (CPU_IS_040_OR_060) {
@@ -25,11 +21,9 @@ static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
 		/* Use no-cache mode, serialized */
 		pgprot_val(vma->vm_page_prot) |= _PAGE_NOCACHE_S;
 	}
-}
 #endif /* CONFIG_SUN3 */
-#else
-#define fb_pgprotect(...) do {} while (0)
 #endif /* CONFIG_MMU */
+}
 
 static inline int fb_is_primary_device(struct fb_info *info)
 {