MIPS/GAS/testsuite: Run SAVE/RESTORE tests across all MIPS16e architectures

	gas/
	* testsuite/gas/mips/mips16e-save.d: Remove `-mmips:isa32
	-mmips:16' from `objdump' flags and `-march=mips32 -mips16' from
	`as' flags.
	* testsuite/gas/mips/mips16e-save-err.d: Remove `-march=mips32'
	from `as' flags.
	* testsuite/gas/mips/mips16e-save.s: Remove the `.set mips16'
	pseudo-op.
	* testsuite/gas/mips/mips16e-save-err.s: Likewise.
	* testsuite/gas/mips/mips.exp: Run SAVE/RESTORE tests across all
	MIPS16e architectures.