mtd: Convert logging messages

Use a more current logging style.

Convert homegrown ERROR/INFO macros to pr_<level>.
Convert homegrown parse_err macros to pr_err and
expand hidden flow control.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>