[PATCH] powerpc: Fix compiling of ppc32

The merging of auxvec.h into asm-powerpc introduced the AT_SYSINFO_EHDR
into the ppc32 build that is used for VDSO.  However, we dont have VDSO
support in the ppc32 tree at this time.  Introducing this define causes
a number of other things to get built with the assumption of VDSO, thus
causing the compile errors for ppc32.

Until we have VDSO on ppc32 we will leave AT_SYSINFO_EHDR a ppc64 only
define.

Signed-off-by: Kumar K. Gala <kumar.gala@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>