MIPS: syscalls: fix indentation of the 'SYSNR' message

It also lacks a whitespace (copy'n'paste error?) and also messes up the
output:

  SYSHDR  arch/mips/include/generated/uapi/asm/unistd_n32.h
  SYSHDR  arch/mips/include/generated/uapi/asm/unistd_n64.h
  SYSHDR  arch/mips/include/generated/uapi/asm/unistd_o32.h
  SYSNR  arch/mips/include/generated/uapi/asm/unistd_nr_n32.h
  SYSNR  arch/mips/include/generated/uapi/asm/unistd_nr_n64.h
  SYSNR  arch/mips/include/generated/uapi/asm/unistd_nr_o32.h
  WRAP    arch/mips/include/generated/uapi/asm/bpf_perf_event.h
  WRAP    arch/mips/include/generated/uapi/asm/ipcbuf.h

After:

  SYSHDR  arch/mips/include/generated/uapi/asm/unistd_n32.h
  SYSHDR  arch/mips/include/generated/uapi/asm/unistd_n64.h
  SYSHDR  arch/mips/include/generated/uapi/asm/unistd_o32.h
  SYSNR   arch/mips/include/generated/uapi/asm/unistd_nr_n32.h
  SYSNR   arch/mips/include/generated/uapi/asm/unistd_nr_n64.h
  SYSNR   arch/mips/include/generated/uapi/asm/unistd_nr_o32.h
  WRAP    arch/mips/include/generated/uapi/asm/bpf_perf_event.h
  WRAP    arch/mips/include/generated/uapi/asm/ipcbuf.h

Present since day 0 of syscall table generation introduction for MIPS.

Fixes: 9bcbf97c ("mips: add system call table generation support")
Cc: <stable@vger.kernel.org> # v5.0+
Signed-off-by: Alexander Lobakin <alobakin@dlink.ru>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Rob Herring <robh@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org