[POWERPC] Fix link errors for allyesconfig

An allyesconfig build creates a .text section that is so big that the
.text.init.refok and .fixup sections are too far away for the relocations
to be fixed up correctly. This patch fixes that by linking all the
relevent text sections for each file together.

Suggested by Paul Mackerras.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>