xtensa: use generic fb.h

The arch uses a verbatim copy of the asm-generic version and does not
add any own implementations to the header, so use asm-generic/fb.h
instead of duplicating code.

Link: http://lkml.kernel.org/r/20170517083545.2115-1-tklauser@distanz.ch
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/xtensa/include/asm/Kbuild

@@ -5,6 +5,7 @@ generic-y += dma-contiguous.h
 generic-y += emergency-restart.h
 generic-y += exec.h
 generic-y += extable.h
+generic-y += fb.h
 generic-y += hardirq.h
 generic-y += irq_regs.h
 generic-y += irq_work.h

arch/xtensa/include/asm/fb.h

@@ -1,12 +0,0 @@
-#ifndef _ASM_FB_H_
-#define _ASM_FB_H_
-#include <linux/fb.h>
-
-#define fb_pgprotect(...) do {} while (0)
-
-static inline int fb_is_primary_device(struct fb_info *info)
-{
-	return 0;
-}
-
-#endif /* _ASM_FB_H_ */