fpga: m10bmc-sec: expose max10 flash update count

Extend the MAX10 BMC Secure Update driver to provide a sysfs file to
expose the flash update count.

Reviewed-by: Tom Rix <trix@redhat.com>
Tested-by: Tianfei Zhang <tianfei.zhang@intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Link: https://lore.kernel.org/r/20220606160038.846236-4-russell.h.weight@intel.com


Signed-off-by: Xu Yilun <yilun.xu@intel.com>