powerpc: fix compiling CONFIG_PPC_TRANSACTIONAL_MEM when CONFIG_ALTIVEC=n

We can't compile a kernel with CONFIG_ALTIVEC=n when
CONFIG_PPC_TRANSACTIONAL_MEM=y.  We currently get:

arch/powerpc/kernel/tm.S:320: Error: unsupported relocation against THREAD_VSCR
arch/powerpc/kernel/tm.S:323: Error: unsupported relocation against THREAD_VR0
arch/powerpc/kernel/tm.S:323: Error: unsupported relocation against THREAD_VR0
etc.

The below fixes this with a sprinkling of #ifdefs.

This was found by mpe with kisskb:
  http://kisskb.ellerman.id.au/kisskb/buildresult/8539442/

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 59dd545..16e77a8 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -555,10 +555,12 @@
 		new->thread.regs->msr |=
 			(MSR_FP | new->thread.fpexc_mode);
 	}
+#ifdef CONFIG_ALTIVEC
 	if (msr & MSR_VEC) {
 		do_load_up_transact_altivec(&new->thread);
 		new->thread.regs->msr |= MSR_VEC;
 	}
+#endif
 	/* We may as well turn on VSX too since all the state is restored now */
 	if (msr & MSR_VSX)
 		new->thread.regs->msr |= MSR_VSX;