i2c-pxa: only define 'blue_murder'-function if DEBUG is #defined

This talkative function is also called on timeouts. As timeouts can
happen on regular writes to EEPROMs (no error case), this creates false
positives.  Giving lots of details is interesting only for developers
anyhow, so just use the function if DEBUG is #defined.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Cc: Roel Kluin <roel.kluin@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>