[ARM] 5245/1: Fix warning about unused return value in drivers/pcmcia

Fix warning when compiling "drivers/pcmcia/soc-common.c"
The return value of the function "device_create_file"
was not used / assigned.

Signed-off-by: Jrgen Schindele <linux@schindele.name>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>