fbdev: geode: don't build on UML

fbdev: geode: don't build on UML

The geode fbdev driver uses struct cpuinfo fields that are not present
on ARCH=um, so don't allow this driver to be built on UML.

Prevents these build errors:

In file included from ../arch/x86/include/asm/olpc.h:7:0,
                 from ../drivers/mfd/cs5535-mfd.c:17:
../arch/x86/include/asm/geode.h: In function ‘is_geode_gx’:
../arch/x86/include/asm/geode.h:16:24: error: ‘struct cpuinfo_um’ has no member named ‘x86_vendor’
  return ((boot_cpu_data.x86_vendor == X86_VENDOR_NSC) &&
../arch/x86/include/asm/geode.h:16:39: error: ‘X86_VENDOR_NSC’ undeclared (first use in this function); did you mean ‘X86_VENDOR_ANY’?
  return ((boot_cpu_data.x86_vendor == X86_VENDOR_NSC) &&
../arch/x86/include/asm/geode.h:17:17: error: ‘struct cpuinfo_um’ has no member named ‘x86’
   (boot_cpu_data.x86 == 5) &&
../arch/x86/include/asm/geode.h:18:17: error: ‘struct cpuinfo_um’ has no member named ‘x86_model’
   (boot_cpu_data.x86_model == 5));
../arch/x86/include/asm/geode.h: In function ‘is_geode_lx’:
../arch/x86/include/asm/geode.h:23:24: error: ‘struct cpuinfo_um’ has no member named ‘x86_vendor’
  return ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
../arch/x86/include/asm/geode.h:23:39: error: ‘X86_VENDOR_AMD’ undeclared (first use in this function); did you mean ‘X86_VENDOR_ANY’?
  return ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
../arch/x86/include/asm/geode.h:24:17: error: ‘struct cpuinfo_um’ has no member named ‘x86’
   (boot_cpu_data.x86 == 5) &&
../arch/x86/include/asm/geode.h:25:17: error: ‘struct cpuinfo_um’ has no member named ‘x86_model’
   (boot_cpu_data.x86_model == 10));

Fixes: 68f5d3f3b654 ("um: add PCI over virtio emulation driver")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Richard Weinberger <richard@nod.at>
Cc: linux-um@lists.infradead.org
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: Andres Salomon <dilinger@queued.net>
Cc: linux-geode@lists.infradead.org
Signed-off-by: Helge Deller <deller@gmx.de>