tpm: Cap the number of PCR banks

tpm: Cap the number of PCR banks

tpm2_get_pcr_allocation() does not cap any upper limit for the number of
banks. Cap the limit to eight banks so that out of bounds values coming
from external I/O cause on only limited harm.

Cc: stable@vger.kernel.org # v5.10+
Fixes: bcfff8384f6c ("tpm: dynamically allocate the allocated_banks array")
Tested-by: Lai Yi <yi1.lai@linux.intel.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>