pxa was missed in the moving of IOMEM to a common definition, so lots of
IOMEM redefined warnings were introduced. So remove pxa IOMEM definition
and fix all the fallout.

Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Haojian Zhuang <haojian.zhuang@marvell.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: rtc-linux@googlegroups.com
Cc: alsa-devel@alsa-project.org