[ARM][gas] Use as_tsktsk instead of as_warn for deprecation messages.

[ARM][gas] Use as_tsktsk instead of as_warn for deprecation messages.

	* config/tc-arm.c (warn_deprecated_sp): Use as_tsktsk instead
	of as_warn for deprecation messages.
	(encode_arm_addr_mode_2): Likewise.
	(check_obsolete): Likewise.
	(do_rd_rm_rn): Likewise.
	(do_co_reg): Likewise.
	(do_setend): Likewise.
	(do_t_mov_cmp): Likewise.
	(do_neon_ldr_str): Likewise.
	(opcode_lookup): Likewise.
	(if_fsm_post_encode): Likewise.
	(md_assemble): Likewise.

	* gas/arm/armv1.l: Remove 'Warning: ' from expected messages
	for deprecations.
	* gas/arm/armv8-a-bad.l: Likewise.
	* gas/arm/armv8-a-it-bad.l: Likewise.
	* gas/arm/depr-swp.l: Likewise.
	* gas/arm/ldsgeb.l: Likewise.
	* gas/arm/ldsgeh.l: Likewise.
	* gas/arm/thumb2_bad_reg.l: Likewise.
	* gas/arm/thumb32.l: Likewise.
	* gas/arm/udf.l: Likewise.
	* gas/arm/vstr-arm-bad.l: Likewise.