cpufreq: amd-pstate: Make amd-pstate unit tests depend on amd-pstate

cpufreq: amd-pstate: Make amd-pstate unit tests depend on amd-pstate

As the unit tests use a symbol from the driver an explicit dependency
is required.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202406222016.R4A2TMs8-lkp@intel.com/
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Perry Yuan <Perry.Yuan@amd.com>
Link: https://lore.kernel.org/r/20240622215219.47911-1-mario.limonciello@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>