kconfig: fix set but not used variables

Some variables were being set but never used, which was triggering
warnings in GCC >= 4.6.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: nobodyAtall <tsogkas@ceid.upatras.gr>
msm7x30: overclocking
mogami: remove undervolt options from Kconfig

with this change we're able to disable undervolt only by changing the defconfigs

Change-Id: I19e0111ee250c1ee2d7b2305366ce5727ef2ff34
Signed-off-by: Michael Bestas <mikeioannina@gmail.com>