LoongArch: Add support for 32_PCREL relocation type

When build and update kernel with the latest upstream binutils and
loongson3_defconfig, module loader fails with:

  kmod: zsmalloc: Unsupport relocation type 99, please add its support.
  kmod: fuse: Unsupport relocation type 99, please add its support.
  kmod: ipmi_msghandler: Unsupport relocation type 99, please add its support.
  kmod: ipmi_msghandler: Unsupport relocation type 99, please add its support.
  kmod: pstore: Unsupport relocation type 99, please add its support.
  kmod: drm_display_helper: Unsupport relocation type 99, please add its support.
  kmod: drm_display_helper: Unsupport relocation type 99, please add its support.
  kmod: drm_display_helper: Unsupport relocation type 99, please add its support.
  kmod: fuse: Unsupport relocation type 99, please add its support.
  kmod: fat: Unsupport relocation type 99, please add its support.

This is because the latest upstream binutils replaces a pair of ADD32
and SUB32 with 32_PCREL, so add support for 32_PCREL relocation type.

Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ecb802d02eeb
Cc: <stable@vger.kernel.org>
Co-developed-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>