mips: fix vdso32 build, again

The generic vdso support adds the same #if hack in two places,
asm/vdso/vdso.h and config-n32-o32-env.c, but only the second
is actually used. The result lacks the BUILD_VDSO32_64 macro,
and that triggers a build error:

./include/linux/page-flags-layout.h:95:2: error: #error "Not enough bits in page flags"

Move the macro into the other place, and remove the duplicated
bits.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: ee38d94a ("page flags: prioritize kasan bits over last-cpuid")
Fixes: 24640f23 ("mips: Add support for generic vDSO")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

arch/mips/include/asm/vdso/vdso.h

@@ -6,16 +6,6 @@
 
 #include <asm/sgidefs.h>
 
-#if _MIPS_SIM != _MIPS_SIM_ABI64 && defined(CONFIG_64BIT)
-
-/* Building 32-bit VDSO for the 64-bit kernel. Fake a 32-bit Kconfig. */
-#undef CONFIG_64BIT
-#define CONFIG_32BIT 1
-#ifndef __ASSEMBLY__
-#include <asm-generic/atomic64.h>
-#endif
-#endif
-
 #ifndef __ASSEMBLY__
 
 #include <asm/asm.h>

arch/mips/vdso/config-n32-o32-env.c

@@ -12,6 +12,7 @@
 
 #define CONFIG_32BIT 1
 #define CONFIG_GENERIC_ATOMIC64 1
+#define BUILD_VDSO32_64
 
 #endif