UPSTREAM: MIPS: vdso: Define BUILD_VDSO32 when building a 32bit kernel

The confinement of the 32bit specific VDSO functions missed to define
BUILD_VDSO32 when building a 32bit MIPS kernel:

arch/mips/vdso/vgettimeofday.c: In function __vdso_clock_gettime:
arch/mips/vdso/vgettimeofday.c:17:9: error: implicit declaration of function __cvdso_clock_gettime32

arch/mips/vdso/vgettimeofday.c: In function __vdso_clock_getres:
arch/mips/vdso/vgettimeofday.c:39:9: error: implicit declaration of function __cvdso_clock_getres_time32

Force the define for 32bit builds in the VDSO Makefile.

Fixes: bf279849ad59 ("lib/vdso: Build 32 bit specific functions in the right context")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul Burton <paulburton@kernel.org>
Link: https://lore.kernel.org/r/87d0bjfaqa.fsf@nanos.tec.linutronix.de



(cherry picked from commit 99570c3da96a0f7aa11c6ad4981776f3adabf3b5)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I00c1cbdbca17f9b9d018e32115ed12cff5c1db18