powerpc/le: Avoid creatng R_PPC64_TOCSAVE relocations for modules.

When building modules with a native le toolchain the linker will
generate R_PPC64_TOCSAVE relocations when it's safe to omit saving r2 on
a plt call.  This isn't helpful in the conext of a kernel module and the
kernel will fail to load those modules with an error like:
	nf_conntrack: Unknown ADD relocation: 109

This patch tells the linker to avoid createing R_PPC64_TOCSAVE
relocations allowing modules to load.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>