bfd: Pass true to ld_plugin_object_p

Since linker calls bfd_plugin_object_p, which calls ld_plugin_object_p,
only for command-line input objects, pass true to ld_plugin_object_p so
that the same input IR file won't be included twice if the new LTO hook,
LDPT_REGISTER_CLAIM_FILE_HOOK_V2 isn't used.

	PR ld/32153
	* plugin.c (bfd_plugin_object_p): Pass true to ld_plugin_object_p.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>