[POWERPC] 85xx: mpc85xx_ads: add in missing of_node_put()

Add in missing of_node_put() after cpm2_pic_init(). This and other coding
style cleanups as suggested by Stephen Rothwell.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>