km/arm: coding style clean up

Address most of the checkpatch issues we found in km_arm and common km
code.

CC: Stefan Roese <sr@denx.de>
CC: Valentin Longchamp <valentin.longchamp@hitachi-powergrids.com>
Signed-off-by: Holger Brunck <holger.brunck@hitachi-powergrids.com>
Reviewed-by: Stefan Roese <sr@denx.de>