[RISCV][NFC] Split PseudoCALL pattern out from instruction
[RISCV][NFC] Split PseudoCALL pattern out from instruction

Since PseudoCALL defines AsmString, it can be generated from assembly,
and so code-gen patterns should be defined separately to be consistent
with the style of the RISCV backend. Other pseudo-instructions exist
that have code-gen patterns defined directly, but these instructions are
purely for code-gen and cannot be written in assembly.

Differential Revision: https://reviews.llvm.org/D64012
Patch by James Clarke.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@366174 91177308-0d34-0410-b5e6-96231b3b80d8

GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm