This patch fixes the following checkpatch warnings:

WARNING:PRINTK_WITHOUT_KERN_LEVEL: printk() should include KERN_<LEVEL> facility level
WARNING:PREFER_PR_LEVEL: Prefer [subsystem eg: netdev]_dbg([subsystem]dev, ... then dev_dbg(dev, ... then pr_debug(...  to printk(KERN_DEBUG ...
WARNING:EMBEDDED_FUNCTION_NAME: Prefer using '"%s...", __func__' to using 'ciintf_slot_ts_enable', this function's name, in a string
CHECK:MACRO_ARG_PRECEDENCE: Macro argument 'level' may be better as '(level)' to avoid precedence issues

There was no consistent style of logging functions used so far.
Convert all logging to the appropriate pr_* macros.
Add a global pr_fmt macro for the whole driver.
Signed-off-by: Stefan Herdler <herdler@nurfuerspam.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>