kobject.h: fix build when CONFIG_HOTPLUG is disabled

When CONFIG_HOTPLUG is not enabled, the inline function add_uevent_var()
needs to have its __attribute__ before the function name/parameters,
otherwise there are syntax errors.

linux-next-20110207/include/linux/kobject.h:232: error: expected ',' or ';' before '{' token

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>