fbdev: sh7760fb: allow modular build

There is no reason to prohibit sh7760fb from being built as a
loadable module as suggested by Geert, so change the config symbol
from bool to tristate to allow that and change the FB dependency as
needed.

Fixes: f75f71b ("fbdev/sh7760fb: Depend on FB=y")
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Acked-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>

Author: rddunlap

drivers/video/fbdev/Kconfig

@@ -1645,8 +1645,8 @@ config FB_COBALT
 	select FB_IOMEM_HELPERS
 
 config FB_SH7760
-	bool "SH7760/SH7763/SH7720/SH7721 LCDC support"
-	depends on FB=y && (CPU_SUBTYPE_SH7760 || CPU_SUBTYPE_SH7763 \
+	tristate "SH7760/SH7763/SH7720/SH7721 LCDC support"
+	depends on FB && (CPU_SUBTYPE_SH7760 || CPU_SUBTYPE_SH7763 \
 		|| CPU_SUBTYPE_SH7720 || CPU_SUBTYPE_SH7721)
 	select FB_IOMEM_HELPERS
 	help