Add fake nvram for Mambo platform
Add fake nvram for Mambo platform

Increases boot-code-coverage (for Mambo):
Lines: 		2043 to 2168 (8.3% to 8.8%)
Functions:	283 to 298   (14.7% to 15.4%)
Branches:	792 to 816   (6.4% to 6.5%)

Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

legoater/skiboot,mikey/skiboot,open-power/skiboot,qemu/skiboot,ddstreet/skiboot,shenki/skiboot,open-power/skiboot,ddstreet/skiboot,legoater/skiboot,open-power/skiboot,apopple/skiboot,csmart/skiboot,shenki/skiboot,csmart/skiboot,mikey/skiboot,qemu/skiboot,stewart-ibm/skiboot,open-power/skiboot,legoater/skiboot,shenki/skiboot,legoater/skiboot,mikey/skiboot,apopple/skiboot,apopple/skiboot,qemu/skiboot,shenki/skiboot,stewart-ibm/skiboot,qemu/skiboot,csmart/skiboot,qemu/skiboot,shenki/skiboot,legoater/skiboot,open-power/skiboot,ddstreet/skiboot,stewart-ibm/skiboot