LoongArch: readelf -d RELASZ excludes .rela.plt size

Before, readelf -d RELASZ is the sum of .rela.dyn size and .rela.plt size.
To consistent with LoongArch lld, RELASZ chang to only the size of .rela.dyn.

bfd/elfnn-loongarch.c

diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index 70a6662..5d5ca19 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -4663,4 +4663,6 @@
 #define elf_backend_hash_symbol elf_loongarch64_hash_symbol
 #define bfd_elfNN_bfd_relax_section loongarch_elf_relax_section
 
+#define elf_backend_dtrel_excludes_plt 1
+
 #include "elfNN-target.h"