kmtest:CcPinRead is badly unreliable on Test WHS

Test KVM and Test VBox have lots of failures, but not this "intermittent" issue, at first glance.

—

Most recent Test WHS builds:
https://reactos.org/testman/compare.php?ids=67835,67839,67841,67844,67858,67920,67922,68252

Result can be:

• success

  CcPinRead: 502 tests executed (0 marked as todo, 0 failures), 0 skipped.

• 1 failure

  CcPinRead_drv.c:459: Test failed: Buffer DE3C1000 not mapped in system space

  // or

  CcPinRead_drv.c:743: Test failed: Length is not MappedLength-sized: 4096

• 2 failures

  CcPinRead_drv.c:459: Test failed: Buffer E0F01000 not mapped in system space

  CcPinRead_drv.c:743: Test failed: Length is not MappedLength-sized: 4096

• "crash"

  Timeout while waiting for the test process

  This case causes all following kmtests to "crash" too:

  C:/Buildslave/Test_WHS/build/modules/rostests/kmtests/kmtest/kmtest.c:268: error 0x00000005: Access is denied.