[NVPTX] Add VRFrame and VRFrameLocal to integer register classes

These registers are used as operands for instructions that expect an
integer register, so they should be added to Int32Regs or Int64Regs
register classes. Otherwise the machine verifier emits an error for
the following LIT tests when LLVM_ENABLE_MACHINE_VERIFIER=1
environment variable is set:

*** Bad machine code: Illegal physical register for instruction ***
- function:    kernel_func
- basic block: %bb.0 entry (0x55c8903d5438)
- instruction: %3:int64regs = LEA_ADDRi64 $vrframelocal, 0
- operand 1:   $vrframelocal
$vrframelocal is not a Int64Regs register.

    CodeGen/NVPTX/call-with-alloca-buffer.ll
    CodeGen/NVPTX/disable-opt.ll
    CodeGen/NVPTX/lower-alloca.ll
    CodeGen/NVPTX/lower-args.ll
    CodeGen/NVPTX/param-align.ll
    CodeGen/NVPTX/reg-types.ll
    DebugInfo/NVPTX/dbg-declare-alloca.ll
    DebugInfo/NVPTX/dbg-value-const-byref.ll

Differential Revision: https://reviews.llvm.org/D110164