fbdev/drm: fix Kconfig submenu mess in "Graphics support"

Submenus of the graphics support "Support for frame buffer devices" and
"Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)" are
broken in half after latest changes for Intel 915 mode setting support.

The DRM subsection is broken because one option is put outside the choice
section it depends on.

The frame buffers part is broken then due to circular dependency.  Fix
this by make Intel frame buffers depend on CONFIG_INTEL_AGP.

Kconfigs are broken by d2f59357


("drm/i915: select framebuffer support automatically").

This is probably not only way to fix this.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>