char/tpm: Fix unitialized usage of data buffer

This patch fixes information leakage to the userspace by initializing
the data buffer to zero.
Reported-by: NPeter Huewe <huewe.external@infineon.com>
Signed-off-by: NPeter Huewe <huewe.external@infineon.com>
Signed-off-by: NMarcel Selhorst <m.selhorst@sirrix.com>
[ Also removed the silly "* sizeof(u8)".  If that isn't 1, we have way
  deeper problems than a simple multiplication can fix.   - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/tpm/tpm.c

@@ -980,7 +980,7 @@ int tpm_open(struct inode *inode, struct file *file)
 		return -EBUSY;
 	}
 
-	chip->data_buffer = kmalloc(TPM_BUFSIZE * sizeof(u8), GFP_KERNEL);
+	chip->data_buffer = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
 	if (chip->data_buffer == NULL) {
 		clear_bit(0, &chip->is_open);
 		put_device(chip->dev);