powerpc: Add new HWCAP bits

POWER10 introduces two new architectural features - ISAv3.1 and matrix
multiply assist (MMA) instructions. Userspace detects the presence
of these features via two HWCAP bits introduced in this patch. These
bits have been agreed to by the compiler and binutils team.

According to ISAv3.1 MMA is an optional feature and software that makes
use of it should first check for availability via this HWCAP bit and use
alternate code paths if unavailable.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Tested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-2-alistair@popple.id.au

arch/powerpc/include/uapi/asm/cputable.h

@@ -50,6 +50,8 @@
 #define PPC_FEATURE2_DARN		0x00200000 /* darn random number insn */
 #define PPC_FEATURE2_SCV		0x00100000 /* scv syscall */
 #define PPC_FEATURE2_HTM_NO_SUSPEND	0x00080000 /* TM w/out suspended state */
+#define PPC_FEATURE2_ARCH_3_1		0x00040000 /* ISA 3.1 */
+#define PPC_FEATURE2_MMA		0x00020000 /* Matrix Multiply Assist */
 
 /*
  * IMPORTANT!