[CodeGen] Fix printing bundles in MIR output

Delay printing the newline until after the opening bracket was
printed, e.g.
  BUNDLE implicit-def $r1, implicit-def $r21, implicit $r1 {
    renamable $r1 = S2_asr_i_r renamable $r1, 1
    renamable $r21 = A2_tfrsi 0
  }
instead of
  BUNDLE implicit-def $r1, implicit-def $r21, implicit $r1
 {    renamable $r1 = S2_asr_i_r renamable $r1, 1
    renamable $r21 = A2_tfrsi 0
  }

llvm-svn: 329719