libnvdimm: mark 'security_show' static again

The security_show() function was made global and __weak at some
point to allow overriding it. The override was removed later, but
it remains global, which causes a warning about the missing
declaration:

drivers/nvdimm/dimm_devs.c:352:9: error: no previous prototype for 'security_show'

This is also not an appropriate name for a global symbol in the
kernel, so just make it static again.

Fixes: 15a8348 ("libnvdimm: Introduce CONFIG_NVDIMM_SECURITY_TEST flag")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20230516201415.556858-3-arnd@kernel.org
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Author: arndb

drivers/nvdimm/dimm_devs.c

@@ -349,7 +349,7 @@ static ssize_t available_slots_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(available_slots);
 
-ssize_t security_show(struct device *dev,
+static ssize_t security_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nvdimm *nvdimm = to_nvdimm(dev);