arm64: vdso32: Define BUILD_VDSO32_64 to correct prototypes

After commit 42874e4e ("arch: vdso: consolidate gettime
prototypes"), there are a couple of errors when building the 32-bit
compat vDSO for arm64:

  arch/arm64/kernel/vdso32/vgettimeofday.c:10:5: error: conflicting types for '__vdso_clock_gettime'; have 'int(clockid_t,  struct old_timespec32 *)' {aka 'int(int,  struct old_timespec32 *)'}
     10 | int __vdso_clock_gettime(clockid_t clock,
        |     ^~~~~~~~~~~~~~~~~~~~
  In file included from arch/arm64/kernel/vdso32/vgettimeofday.c:8:
  include/vdso/gettime.h:16:5: note: previous declaration of '__vdso_clock_gettime' with type 'int(clockid_t,  struct __kernel_timespec *)' {aka 'int(int,  struct __kernel_timespec *)'}
     16 | int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts);
        |     ^~~~~~~~~~~~~~~~~~~~
  arch/arm64/kernel/vdso32/vgettimeofday.c:28:5: error: conflicting types for '__vdso_clock_getres'; have 'int(clockid_t,  struct old_timespec32 *)' {aka 'int(int,  struct old_timespec32 *)'}
     28 | int __vdso_clock_getres(clockid_t clock_id,
        |     ^~~~~~~~~~~~~~~~~~~
  include/vdso/gettime.h:15:5: note: previous declaration of '__vdso_clock_getres' with type 'int(clockid_t,  struct __kernel_timespec *)' {aka 'int(int,  struct __kernel_timespec *)'}
     15 | int __vdso_clock_getres(clockid_t clock, struct __kernel_timespec *res);
        |     ^~~~~~~~~~~~~~~~~~~

The type of the second parameter in __vdso_clock_getres() and
__vdso_clock_gettime() changes based on whether compiling for 32-bit vs.
64-bit, which is controlled by CONFIG_64BIT or the preprocessor macro
BUILD_VDSO32_64, which denotes a 32-bit vDSO is being built for a 64-bit
architecture. Since this situation is the latter case, define
BUILD_VDSO32_64 before the inclusion of include/vdso/gettime.h to clear
up the warning

Fixes: 42874e4e ("arch: vdso: consolidate gettime prototypes")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Closes: https://lore.kernel.org/CA+G9fYtV6X=c3JVTTAX89_=wc+uqLpzggnsbGSx-98m_5yd5yw@mail.gmail.com/Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/ZWCRWArzbTYUjvon@finisterre.sirena.org.uk/Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm64/kernel/vdso32/vgettimeofday.c

@@ -5,6 +5,7 @@
  * Copyright (C) 2018 ARM Limited
  *
  */
+#define BUILD_VDSO32_64
 #include <vdso/gettime.h>
 
 int __vdso_clock_gettime(clockid_t clock,