sysfs: small header file cleanup for SYSFS=n

Convert sysfs_remove_bin_file() to have a return type of 'void' for
!CONFIG_SYSFS configurations.  Also removes unnecessary colons from empty
void functions.

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