[RISCV] Remove unneeded anyext/trunc patterns from RISCVGISel.td. NFC

We have code to manually select these as copies already. There are
multiple combinations of types that need to be supported due to
s32 and s16 being legal for the GPR register bank. It's simpler
to handle generically than to write out all the patterns.

Author: topperc

llvm/lib/Target/RISCV/RISCVGISel.td

@@ -138,9 +138,7 @@ def : LdPat<extloadi16, LH, i32>;
 def : StPat<truncstorei8, SB, GPR, i32>;
 def : StPat<truncstorei16, SH, GPR, i32>;
 
-def : Pat<(anyext (i32 GPR:$src)), (COPY GPR:$src)>;
 def : Pat<(sext (i32 GPR:$src)), (ADDIW GPR:$src, 0)>;
-def : Pat<(i32 (trunc GPR:$src)), (COPY GPR:$src)>;
 
 def : Pat<(sext_inreg (i64 (add GPR:$rs1, simm12_lo:$imm)), i32),
           (ADDIW GPR:$rs1, simm12_lo:$imm)>;