lmb: Fix lmb property's defination under struct lmb

Under struct lmb {} the lmb property's should be defined only if
CONFIG_LMB_MEMORY_REGIONS is defined.

Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/c24a2b1d6f5db4eb65393f6a77fae129b30b6233.1657183534.git.michal.simek@amd.com