arch/parisc: Implement <asm/fb.h> with generic helpers

Replace the architecture's fbdev helpers with the generic ones
from <asm-generic/fb.h>. On PARISC, pgprot_writecombine() and
pgprot_noncached() are the same; hence no functional changes.

v3:
	* use default implementation for fb_pgprotect() (Arnd)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Helge Deller <deller@gmx.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230417125651.25126-15-tzimmermann@suse.de

arch/parisc/include/asm/fb.h

@@ -2,23 +2,13 @@
 #ifndef _ASM_FB_H_
 #define _ASM_FB_H_
 
-#include <linux/fb.h>
-#include <linux/fs.h>
-#include <asm/page.h>
-
-static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
-				unsigned long off)
-{
-	pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE;
-}
+struct fb_info;
 
 #if defined(CONFIG_STI_CORE)
 int fb_is_primary_device(struct fb_info *info);
-#else
-static inline int fb_is_primary_device(struct fb_info *info)
-{
-	return 0;
-}
+#define fb_is_primary_device fb_is_primary_device
 #endif
 
+#include <asm-generic/fb.h>
+
 #endif /* _ASM_FB_H_ */