Fix backwards incompatibility introduced by RV128 opcodes in #112

Adding RV128 shift opcodes changed what metadata we emit for SLLI, SRLI,
and SRAI.  Thus, downstream tooling that relies on these to connote the
RV64 variants of these instructions is semantically affected.

Fix by reverting SLLI etc. to being the RV64 variants.

rv32_i

@@ -1,3 +1,3 @@
-$pseudo_op rv128_i::slli slli rd rs1 shamtw 31..25=0  14..12=1 6..2=0x04 1..0=3
-$pseudo_op rv128_i::srli srli rd rs1 shamtw 31..25=0  14..12=5 6..2=0x04 1..0=3
-$pseudo_op rv128_i::srai srai rd rs1 shamtw 31..25=32 14..12=5 6..2=0x04 1..0=3
+$pseudo_op rv128_i::slli slli_rv32 rd rs1 shamtw 31..25=0  14..12=1 6..2=0x04 1..0=3
+$pseudo_op rv128_i::srli srli_rv32 rd rs1 shamtw 31..25=0  14..12=5 6..2=0x04 1..0=3
+$pseudo_op rv128_i::srai srai_rv32 rd rs1 shamtw 31..25=32 14..12=5 6..2=0x04 1..0=3

rv64_i

@@ -4,9 +4,9 @@ lwu     rd rs1       imm12 14..12=6 6..2=0x00 1..0=3
 ld      rd rs1       imm12 14..12=3 6..2=0x00 1..0=3
 sd     imm12hi rs1 rs2 imm12lo 14..12=3 6..2=0x08 1..0=3
 
-$pseudo_op rv128_i::slli slli   rd rs1 31..26=0  shamtd 14..12=1 6..2=0x04 1..0=3
-$pseudo_op rv128_i::srli srli   rd rs1 31..26=0  shamtd 14..12=5 6..2=0x04 1..0=3
-$pseudo_op rv128_i::srai srai   rd rs1 31..26=16 shamtd 14..12=5 6..2=0x04 1..0=3
+slli   rd rs1 31..26=0  shamtd 14..12=1 6..2=0x04 1..0=3
+srli   rd rs1 31..26=0  shamtd 14..12=5 6..2=0x04 1..0=3
+srai   rd rs1 31..26=16 shamtd 14..12=5 6..2=0x04 1..0=3
 
 addiw   rd rs1 imm12            14..12=0 6..2=0x06 1..0=3
 slliw   rd rs1 31..25=0  shamtw 14..12=1 6..2=0x06 1..0=3

unratified/rv128_i

@@ -16,7 +16,6 @@ ldu     rd rs1       imm12 14..12=7 6..2=0x00 1..0=3
 
 sq     imm12hi rs1 rs2 imm12lo 14..12=4 6..2=0x08 1..0=3
 
-# RV32 and RV64 versions of these are in opcodes-pseudo
-slli    rd rs1 31..27=0  shamtq 14..12=1 6..2=0x04 1..0=3
-srli    rd rs1 31..27=0  shamtq 14..12=5 6..2=0x04 1..0=3
-srai    rd rs1 31..27=8  shamtq 14..12=5 6..2=0x04 1..0=3
+$pseudo_op rv64_i::slli slli_rv128 rd rs1 31..27=0  shamtq 14..12=1 6..2=0x04 1..0=3
+$pseudo_op rv64_i::srli srli_rv128 rd rs1 31..27=0  shamtq 14..12=5 6..2=0x04 1..0=3
+$pseudo_op rv64_i::srai srai_rv128 rd rs1 31..27=8  shamtq 14..12=5 6..2=0x04 1..0=3