[ARM] fix impd1.c build warning

  CC      arch/arm/mach-integrator/impd1.o
arch/arm/mach-integrator/impd1.c: In function `impd1_probe':
arch/arm/mach-integrator/impd1.c:408: warning: too few arguments for format

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