thermal: gov_power_allocator: Rearrange local variables

Rearrange the order of local variable definitions in multiple functions
so as to follow the kernel coding style in that respect.

Also, move local variable definitions located in nested code blocks to
the beginning of each function to improve the visibility of all local
variables in use.

This change is not expected to alter the general functionality.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>