firmware: imx: scu-pd: enlarge PD range for mu_b

The range of resources for Messaging Units side B needs to contain
all the possible MUB resource available: starting from MU_5B up to
MU_13B.
This patch is needed to enable MU_8B for the 'imx-shmem-net' driver
which allows two OS partitions communicating via MUs without Hypervisor.

Signed-off-by: Sebastien Fagard <sebastien.fagard@nxp.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>