nvdimm/region: Fix kernel-doc

nvdimm/region: Fix kernel-doc

drivers/nvdimm/region_devs.c:1103: warning: expecting prototype for nvdimm_flush(). Prototype was for generic_nvdimm_flush() instead.

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2209
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220919061428.102883-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>