target/ppc: ignore third argument in slbmfev/slbmfee

POWER9 added an extra third parameter to these instructions.
Ignore it instead of generating an invalid instruction exception.

See "4.10.7.2 SLB Management Instructions" in the POWER9 User's Manual.

This allows entering the kernel debugger on AIX 7.2.

target/ppc/translate.c

@@ -6794,8 +6794,8 @@ GEN_HANDLER2(mtsr_64b, "mtsr", 0x1F, 0x12, 0x06, 0x0010F801, PPC_SEGMENT_64B),
 GEN_HANDLER2(mtsrin_64b, "mtsrin", 0x1F, 0x12, 0x07, 0x001F0001,
              PPC_SEGMENT_64B),
 GEN_HANDLER2(slbmte, "slbmte", 0x1F, 0x12, 0x0C, 0x001F0001, PPC_SEGMENT_64B),
-GEN_HANDLER2(slbmfee, "slbmfee", 0x1F, 0x13, 0x1C, 0x001F0001, PPC_SEGMENT_64B),
-GEN_HANDLER2(slbmfev, "slbmfev", 0x1F, 0x13, 0x1A, 0x001F0001, PPC_SEGMENT_64B),
+GEN_HANDLER2(slbmfee, "slbmfee", 0x1F, 0x13, 0x1C, 0x001E0001, PPC_SEGMENT_64B),
+GEN_HANDLER2(slbmfev, "slbmfev", 0x1F, 0x13, 0x1A, 0x001E0001, PPC_SEGMENT_64B),
 GEN_HANDLER2(slbfee_, "slbfee.", 0x1F, 0x13, 0x1E, 0x001F0000, PPC_SEGMENT_64B),
 #endif
 GEN_HANDLER(tlbia, 0x1F, 0x12, 0x0B, 0x03FFFC01, PPC_MEM_TLBIA),