[POWERPC] Add cpu feature for SPE handling

Make it so that SPE support can be determined at runtime.  This is similiar
to how we handle AltiVec.  This allows us to have SPE support built in and
work on processors with and without SPE.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 4074c0b..21d889e 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -504,9 +504,11 @@
 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 #endif /* CONFIG_ALTIVEC */
 #ifdef CONFIG_SPE
+BEGIN_FTR_SECTION
 	oris	r0,r0,MSR_SPE@h	 /* Disable SPE */
 	mfspr	r12,SPRN_SPEFSCR /* save spefscr register value */
 	stw	r12,THREAD+THREAD_SPEFSCR(r2)
+END_FTR_SECTION_IFSET(CPU_FTR_SPE)
 #endif /* CONFIG_SPE */
 	and.	r0,r0,r11	/* FP or altivec or SPE enabled? */
 	beq+	1f
@@ -542,8 +544,10 @@
 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 #endif /* CONFIG_ALTIVEC */
 #ifdef CONFIG_SPE
+BEGIN_FTR_SECTION
 	lwz	r0,THREAD+THREAD_SPEFSCR(r2)
 	mtspr	SPRN_SPEFSCR,r0		/* restore SPEFSCR reg */
+END_FTR_SECTION_IFSET(CPU_FTR_SPE)
 #endif /* CONFIG_SPE */
 
 	lwz	r0,_CCR(r1)