Linux PPC: Fix build failures on kernels built without CONFIG_SPE

We do a simple ifdef to avoid calling enable_kernel_spe()/
disable_kernel_spe() on PowerPC.

Reported-by: Rich Ercolani <Rincebrain@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Tested-by: Georgy Yakovlev <gyakovlev@gentoo.org>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14233
Closes #14244

include/os/linux/kernel/linux/simd_powerpc.h

@@ -69,6 +69,7 @@
 #define	kfpu_allowed()			1
 
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0)
+#ifdef CONFIG_SPE
 #define	kfpu_begin()				\
 	{					\
 		preempt_disable();		\
@@ -83,6 +84,20 @@
 		disable_kernel_altivec();	\
 		preempt_enable();		\
 	}
+#else /* CONFIG_SPE */
+#define	kfpu_begin()				\
+	{					\
+		preempt_disable();		\
+		enable_kernel_altivec();	\
+		enable_kernel_vsx();		\
+	}
+#define	kfpu_end()				\
+	{					\
+		disable_kernel_vsx();		\
+		disable_kernel_altivec();	\
+		preempt_enable();		\
+	}
+#endif
 #else
 /* seems that before 4.5 no-one bothered */
 #define	kfpu_begin()