e1000: fix CONFIG_PM blocks

e1000_suspend is called even when !CONFIG_PM. The non-PM code inside of it
is properly #ifdef'd. This fixes the compiler warnings when !CONFIG_PM.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>