fbdev: fbmem: mark get_fb_unmapped_area() static

There is a global function with this name on sparc, but no
global declaration:

drivers/video/fbdev/core/fbmem.c:1469:15: error: no previous prototype for 'get_fb_unmapped_area'

Make the generic definition static to avoid this warning. On
sparc, this is never seen.

Edit by Helge:
Update Kconfig text as suggested by Geert Uytterhoeven.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NHelge Deller <deller@gmx.de>

drivers/video/fbdev/Kconfig

@@ -124,7 +124,7 @@ config FB_PROVIDE_GET_FB_UNMAPPED_AREA
 	depends on FB
 	help
 	  Allow generic frame-buffer to provide get_fb_unmapped_area
-	  function.
+	  function to provide shareable character device support on nommu.
 
 menuconfig FB_FOREIGN_ENDIAN
 	bool "Framebuffer foreign endianness support"

drivers/video/fbdev/core/fbmem.c

@@ -1468,7 +1468,7 @@ __releases(&info->lock)
 }
 
 #if defined(CONFIG_FB_PROVIDE_GET_FB_UNMAPPED_AREA) && !defined(CONFIG_MMU)
-unsigned long get_fb_unmapped_area(struct file *filp,
+static unsigned long get_fb_unmapped_area(struct file *filp,
 				   unsigned long addr, unsigned long len,
 				   unsigned long pgoff, unsigned long flags)
 {