tpm: Lock TPM chip in tpm_pm_suspend() first

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

tpm: Lock TPM chip in tpm_pm_suspend() first

Setting TPM_CHIP_FLAG_SUSPENDED in the end of tpm_pm_suspend() can be racy

according, as this leaves window for tpm_hwrng_read() to be called while

the operation is in progress. The recent bug report gives also evidence of

this behaviour.

Aadress this by locking the TPM chip before checking any chip->flags both

in tpm_pm_suspend() and tpm_hwrng_read(). Move TPM_CHIP_FLAG_SUSPENDED

check inside tpm_get_random() so that it will be always checked only when

the lock is reserved.