Fix all failing FPXX tests for tx39-elf.

Fix all failing FPXX tests for tx39-elf.

ld/testsuite/

	* ld-mips-elf/attr-gnu-4-00.d: Relax check for ISA extension.
	* ld-mips-elf/attr-gnu-4-01.d: Likewise.
	* ld-mips-elf/attr-gnu-4-02.d: Likewise.
	* ld-mips-elf/attr-gnu-4-03.d: Likewise.
	* ld-mips-elf/attr-gnu-4-08.d: Likewise.
	* ld-mips-elf/attr-gnu-4-10.d: Likewise.
	* ld-mips-elf/attr-gnu-4-11.d: Likewise.
	* ld-mips-elf/attr-gnu-4-18.d: Likewise.
	* ld-mips-elf/attr-gnu-4-20.d: Likewise.
	* ld-mips-elf/attr-gnu-4-22.d: Likewise.
	* ld-mips-elf/attr-gnu-4-28.d: Likewise.
	* ld-mips-elf/attr-gnu-4-30.d: Likewise.
	* ld-mips-elf/attr-gnu-4-33.d: Likewise.
	* ld-mips-elf/attr-gnu-4-38.d: Likewise.
	* ld-mips-elf/attr-gnu-4-44.d: Likewise.