cpufreq: amd-pstate-ut: Remove module parameter access

In amd-pstate-ut, shared memory-based systems call
get_shared_mem() as part of amd_pstate_ut_check_enabled()
function. This function was written when CONFIG_X86_AMD_PSTATE
was tristate config and amd_pstate can be built as a module.

Currently CONFIG_X86_AMD_PSTATE is a boolean config and module
parameter shared_mem is removed. But amd-pstate-ut code still
accesses this module parameter. Remove those accesses.

Fixes: 456ca88d ("cpufreq: amd-pstate: change amd-pstate driver to be built-in type")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Meng Li <li.meng@amd.com>
Reviewed-by: Wyes Karny <wyes.karny@amd.com>
Suggested-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>