fbdev: Replace fb_pgprotect() with pgprot_framebuffer()

Rename the fbdev mmap helper fb_pgprotect() to pgprot_framebuffer().
The helper sets VMA page-access flags for framebuffers in device I/O
memory.

Also clean up the helper's parameters and return value. Instead of
the VMA instance, pass the individial parameters separately: existing
page-access flags, the VMAs start and end addresses and the offset
in the underlying device memory rsp file. Return the new page-access
flags. These changes align pgprot_framebuffer() with other pgprot_()
functions.

v4:
	* fix commit message (Christophe)
v3:
	* rename fb_pgprotect() to pgprot_framebuffer() (Arnd)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230922080636.26762-3-tzimmermann@suse.de

include/asm-generic/fb.h

@@ -12,14 +12,14 @@
 #include <linux/pgtable.h>
 
 struct fb_info;
-struct file;
 
-#ifndef fb_pgprotect
-#define fb_pgprotect fb_pgprotect
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
+#ifndef pgprot_framebuffer
+#define pgprot_framebuffer pgprot_framebuffer
+static inline pgprot_t pgprot_framebuffer(pgprot_t prot,
+					  unsigned long vm_start, unsigned long vm_end,
+					  unsigned long offset)
 {
-	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
+	return pgprot_writecombine(prot);
 }
 #endif