powerpc/sstep: Add tests for prefixed floating-point load/stores

Add tests for the prefixed versions of the floating-point load/stores
that are currently tested. This includes the following instructions:
  * Prefixed Load Floating-Point Single (plfs)
  * Prefixed Load Floating-Point Double (plfd)
  * Prefixed Store Floating-Point Single (pstfs)
  * Prefixed Store Floating-Point Double (pstfd)

Skip the new tests if ISA v3.10 is unsupported.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[mpe: Fix conflicts with ppc-opcode.h changes]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200525025923.19843-2-jniethe5@gmail.com
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 90ae33a..4c0bdaf 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -266,6 +266,10 @@
 #define PPC_INST_BRANCH_COND		0x40800000
 
 /* Prefixes */
+#define PPC_INST_LFS			0xc0000000
+#define PPC_INST_STFS			0xd0000000
+#define PPC_INST_LFD			0xc8000000
+#define PPC_INST_STFD			0xd8000000
 #define PPC_PREFIX_MLS			0x06000000
 #define PPC_PREFIX_8LS			0x04000000