Refine rvp (#409)

* rvp: Add P extension

This commit add encodings for P Extension:
https://www.jhauser.us/RISCV/ext-P/RVP-instrEncodings-015.pdf
Signed-off-by: 2011eric <201165r1c@gmail.com>

* rvp: rename pmqwacc/mqrwacc

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: pdif has been renamed by pabd

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: fix some missing characters in instructions name

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: ppack has been renamed by ppair

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: add missing instructions

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: remove old grevi

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: convert 56 RV32 scalar instructions to pseudo-instructions of RV64 equivalents

Based on RVP-instrEncodings-019.pdf, converted RV32
scalar instructions that share the same encoding with RV64 packed-word
instructions to pseudo-instructions.

Instructions converted (56 total):
- Pages 4-8: sslai, ssha, sshar (3)
- Page 9: sadd, aadd, saddu, aaddu, ssub, asub, ssubu, asubu (8)
- Page 10: mul.h01, macc.h01, mulu.h01, maccu.h01 (4)
- Page 11: sh1sadd (1)
- Page 12: mul/macc/mulu/maccu/mulsu/maccsu.h00/h11 (12)
- Page 14: mqacc.h01, mqracc.h01 (2)
- Page 15: mseq, mslt, msltu (3)
- Page 16: mulhr, mhacc, mhracc, mulhru, mhaccu, mhraccu, mulh.h0/h1,
  mulhsu.h0/h1, mhacc.h0/h1, mhaccsu.h0/h1, mulhrsu, mhaccsu, mhraccsu,
  mulq, mulqr, mqacc.h00/h11, mqracc.h00/h11 (23)

Also removed packbt/packtb/packt pseudo-instructions that referenced
non-existent rv64_p instructions.

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: align indent and add comment by page

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: fix mnemonic typo

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

* rvp: add P-extension scalar pseudo-ops to emitted_pseudo_ops

---------

Signed-off-by: 2011eric <201165r1c@gmail.com>
Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>
Co-authored-by: 2011eric <201165r1c@gmail.com>

Author: chihminchao

arg_lut.csv

@@ -103,3 +103,13 @@
 "c_rs2_e", 6, 3
 "rd_e", 11, 8
 "rs2_e", 24, 21
+"p_imm10", 24, 15
+"p_imm8", 23, 16
+"p_w_uimm3", 22, 20
+"p_w_uimm4", 23, 20
+"p_w_uimm5", 24, 20
+"p_w_uimm6", 25, 20
+"p_w", 26, 25
+"p_rd_p", 11, 8
+"p_rs1_p", 19, 16
+"p_rs2_p", 24, 21