Call to dev_dbg in dataflash_read() is located to early, before
command[] is initialize to correct values, so it end up printing
values from previous invocation. Move it such that it prints current
call's values.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>