um: harddog: add missing MODULE_DESCRIPTION() macro

With ARCH=um, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in arch/um/drivers/harddog.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://patch.msgid.link/20240702-md-um-arch-um-drivers-v1-1-79e4f50b5bab@quicinc.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>