drivers: fpga: intel_sdm_mb: Flush cache before FPGA configuration

drivers: fpga: intel_sdm_mb: Flush cache before FPGA configuration

FPGA configuration encounters failure when the cache is not flushed.
Add cache flushing to the memory region that holds the FPGA
configuration bitstream.

Signed-off-by: Naresh Kumar Ravulapalli <nareshkumar.ravulapalli@altera.com>
Link: https://lore.kernel.org/r/20250506012851.30039-1-nareshkumar.ravulapalli@altera.com
Signed-off-by: Michal Simek <michal.simek@amd.com>