[RISCV] Remove unneeded code from RISCVPostRAExpandPseudo::expandMovImm. NFC

We accidentally left a call to generateInstSeq when we rewrote the
code to use the X86InstrInfo::movImm.

Author: topperc

llvm/lib/Target/RISCV/RISCVPostRAExpandPseudoInsts.cpp

@@ -89,10 +89,6 @@ bool RISCVPostRAExpandPseudo::expandMovImm(MachineBasicBlock &MBB,
 
   int64_t Val = MBBI->getOperand(1).getImm();
 
-  RISCVMatInt::InstSeq Seq =
-      RISCVMatInt::generateInstSeq(Val, MBB.getParent()->getSubtarget());
-  assert(!Seq.empty());
-
   Register DstReg = MBBI->getOperand(0).getReg();
   bool DstIsDead = MBBI->getOperand(0).isDead();
   bool Renamable = MBBI->getOperand(0).isRenamable();