pr_err() are replaced with dev_err() so information about
device the error logs refer to is also included.

pr_debug() at beginning of each function are removed
as they are likely very rarely used and can always be
added again when doing any serious debugging.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>