Currently when handling an invalid -march or -mcpu option on a toolchain without an explicit --with-mode configuration
and compiling without an explicit -mthumb or -marm the arm specs end up calling arm_target_thumb_only to determine
the "thumbness" of the target, which involves parsing the architecture or cpu name. But the functions doing that
parsing also emit error messages and hints on invalid arguments. Later when we parse the architecture or cpu string to
as part of the canonicalisation process (arm_canon_arch_option) we end up emitting the errors again.

The solution in this patch is to silence the errors during the arm_target_thumb_only processing so that they are not emitted
twice. arm_canon_arch_option is guaranteed to run as well, so it can emit the errors and hints that it needs.

Bootstrapped and tested on arm-none-linux-gnueabihf.

Checked that we emit the arch/cpu hints for invalid -march/-mcpu options only once when no "thumbness" options were specified
during configuration or invocation.

	PR target/83193
	* common/config/arm/arm-common.c (arm_parse_arch_option_name):
	Accept complain bool parameter.  Only emit errors if it is true.
	(arm_parse_cpu_option_name): Likewise.
	(arm_target_thumb_only): Adjust callers of the above.
	* config/arm/arm-protos.h (arm_parse_cpu_option_name): Adjust
	prototype to take a default true bool parameter.
	(arm_parse_arch_option_name): Likewise.

From-SVN: r258389