[PATCH] arlan: module parameter fixes

Make sure the code compiles with and without ARLAN_ENTRY_EXIT_DEBUGGING.
Only provide parameter descriptions when parameters are defined.
Remove "arlan_"-prefix to shape up built-in parameter names:

arlan.arlan_debug -> arlan.debug
arlan.arlan_EEPROM_bad -> arlan.EEPROM_bad
arlan.arlan_entry_and_exit_debug -> arlan.entry_and_exit_debug
arlan.arlan_entry_debug -> arlan.entry_debug
arlan.arlan_exit_debug -> arlan.exit_debug

Signed-off-by: Magnus Damm <damm@opensource.se>