scmi: translate the resource only when livetree is not activated

Call the translation function on the ofnode_read_resource result only
when the livetree is not activated.

Today of_address_to_resource() calls ofnode_read_resource() for livetree
support and fdt_get_resource() when livetree is not supported.

The fdt_get_resource() doesn't do the address translation
so when it is required when livetree is activated but this address
translation is already done by ofnode_read_resource().

Fixes: 240720e9 ("firmware: scmi: mailbox/smt agent device")
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>