Clean up the IFUNC implementations for powerpc in order to remove
unneeded macro definitions.
Tested on ppc64le with and without --disable-multi-arch flag.
* sysdeps/powerpc/powerpc64/multiarch/memset-power4.S: Define the
implementation-specific function name and remove unneeded macros
definition.
* sysdeps/powerpc/powerpc64/multiarch/memset-power6.S: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/memset-power7.S: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/memset-power8.S: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/memset-ppc64.S: Likewise.
* sysdeps/powerpc/powerpc64/memset.S: Set a default function name if
not defined and pass as parameter to macros accordingly.
* sysdeps/powerpc/powerpc64/power4/memset.S: Likewise.
* sysdeps/powerpc/powerpc64/power6/memset.S: Likewise.
* sysdeps/powerpc/powerpc64/power7/memset.S: Likewise.
* sysdeps/powerpc/powerpc64/power8/memset.S: Likewise.
This patch cleanups the multiarch bzero for powerpc64 by remove
the multiarch objects and use instead the the memset embedded
implementation presented in each multiarch optimization. The
code generate is essentially the same, but the TB_TOCLESS (which
is not essential).