firmware: arm_scmi: Add optional flags to extended names helper

Some recently added SCMI protocols needs an additional flags parameter to
be able to properly configure the command used to query the extended name
of a resource.

Modify extended_name_get helper accordingly.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20231114145449.3136412-1-cristian.marussi@arm.com


Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>