firmware: arm_scmi: Implement arm,no-completion-irq property

firmware: arm_scmi: Implement arm,no-completion-irq property

Implement new property arm,no-completion-irq, which sets all SCMI
operation into poll mode. This is meant to work around uncooperative
SCP implementations, which do not generate completion interrupts.
This applies to mbox/shmem based implementations.

With this property set, such implementations which do not generate
interrupts can be interacted with, until they are fixed to generate
interrupts properly.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Message-Id: <20260117010241.186685-2-marek.vasut+renesas@mailbox.org>
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>