lib/raid6/test/Makefile: Add avx512 gen_syndrome and recovery functions

Adding avx512 gen_syndrome and recovery functions so as to allow code to
be compiled and tested successfully in userspace.

This patch is tested in userspace and improvement in performace is
observed.

Cc: H. Peter Anvin <[e-mail]>
Cc: Jim Kukunas <[e-mail]>
Cc: Fenghua Yu <[e-mail]>
Signed-off-by: Megha Dey <[e-mail]>
Signed-off-by: Gayatri Kammela <[e-mail]>
Reviewed-by: Fenghua Yu <[e-mail]>
Signed-off-by: Shaohua Li <[e-mail]>

lib/raid6/test/Makefile

···
 endif
 
 ifeq ($(IS_X86),yes)
-        OBJS   += mmx.o sse1.o sse2.o avx2.o recov_ssse3.o recov_avx2.o
+        OBJS   += mmx.o sse1.o sse2.o avx2.o recov_ssse3.o recov_avx2.o avx512.o recov_avx512.o
         CFLAGS += $(shell echo "vpbroadcastb %xmm0, %ymm1" |	\
                     gcc -c -x assembler - >&/dev/null &&	\
                     rm ./-.o && echo -DCONFIG_AS_AVX2=1)
+	CFLAGS += $(shell echo "vpmovm2b %k1, %zmm5" |          \
+		    gcc -c -x assembler - >&/dev/null &&        \
+		    rm ./-.o && echo -DCONFIG_AS_AVX512=1)
 else ifeq ($(HAS_NEON),yes)
         OBJS   += neon.o neon1.o neon2.o neon4.o neon8.o
         CFLAGS += -DCONFIG_KERNEL_MODE_NEON=1