platform/x86: dell_rbu: Unify format of the printed messages

Here we do:
- unify all message to have module name prefix via pr_fmt()
- replace printk(LEVEL ... ) with pr_level(...)
- drop __func__ from messages
- join string literals to be on one line
- drop trailing periods and spaces

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>