For DMC firmware header version 3, the firmware load address is stored in dmc_info->start_mmioaddr and later used by dmc_load_program().
Unlike the MMIO address table, the firmware load address is not validated. Add a sanity check to ensure it is within the valid range.
BSpec: 69671, 68378 (cherry picked from commit 5e47ee5c76ca9becde8df4ad5202845b7ffcbc4c)