cpufreq: amd-pstate-ut: Skip tests when amd-pstate driver is not active

In the Linux kernel, the following vulnerability has been resolved:

cpufreq: amd-pstate-ut: Skip tests when amd-pstate driver is not active

The crash issue may occur when modprobe amd_pstate_ut on intel platform.

amd_pstate_ut: 1 amd_pstate_ut_acpi_cpc_valid success!
amd_pstate_ut: 2 amd_pstate_ut_check_enabled success!
BUG: kernel NULL pointer dereference, address: 0000000000000080
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] SMP NOPTI
CPU: 0 PID: 20300 Comm: modprobe
Kdump: loaded Tainted: G O 6.6.0-0010.rc1.ctl4.x86_64 #1
Hardware name: FiberHome R2200 V5/Xeon Boards, BIOS 3.1a 02/24/2020
RIP: 0010:amd_pstate_ut_check_perf+0x141/0x280 [amd_pstate_ut]
Call Trace:
<TASK>
amd_pstate_ut_init+0x1b/0xff0 [amd_pstate_ut]
? __pfx_amd_pstate_ut_init+0x10/0x10 [amd_pstate_ut]
do_one_initcall+0x42/0x2e0
? kmalloc_trace+0x26/0x90
do_init_module+0x60/0x240
__se_sys_init_module+0x185/0x1c0
do_syscall_64+0x62/0x190
entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>

Add state detection to amd pstate driver to prevent amd_pstate_ut driver
from testing on non-AMD platforms.

(ML: adjust title)