mach-doubleshot: underclock and overclock settings enabled

Enabling available lower and higher frequencies for doubleshot
on a safe voltage. 96mhz - 1512mhz are safe frequencies for
different doubleshot revisions.
(A long 1.5 year of testing on cm9 doubleshot proves this so far.)

Using #ifdef CONFIG_MACH_DOUBLESHOT separates the freq/voltage
tables and table selection from other MACH's.

Change-Id: I4e1f7a848f1be64de22db8adf44a86ad2615b7ca