arm: Add cde feature support for Cortex-M55 CPU.

arm: Add cde feature support for Cortex-M55 CPU.

This patch adds cde feature (optional) support for Cortex-M55 CPU, please refer
[1] for more details. To use this feature we need to specify +cdecpN
(e.g. -mcpu=cortex-m55+cdecp<N>), where N is the coprocessor number 0 to 7.

gcc/ChangeLog:

2023-01-13  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

	* common/config/arm/arm-common.cc (arm_canon_arch_option_1): Ignore cde
	options for -mlibarch.
	* config/arm/arm-cpus.in (begin cpu cortex-m55): Add cde options.
	* doc/invoke.texi (CDE): Document options for Cortex-M55 CPU.

gcc/testsuite/ChangeLog:

2023-01-13  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

	* gcc.target/arm/multilib.exp: Add multilib tests for Cortex-M55 CPU.