mtd: dataflash: Replace pr_debug, printk with dev_* functions

Lion's share of calls to pr_debug in this driver follow the pattern of
pr_debug("%s <message>", dev_name(<dev>), <arguments>), which should
be semantically identical to dev_dbg(<dev>, "<message>", <arguments>),
so replace such occurencies to simplify the code.

Convert the small minority of pr_debug that do not follow pattern from
above to use dev_dbg as well, for the sake of consistency.

Convert similar patter of printk(KERN_ERR, "%s: ...", dev_name(...),
...) to use dev_err instead.

No functional change intended.

Cc: cphealy@gmail.com
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>
Tested-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>