tpm: missing tpm_chip_put in tpm_get_random()

Regression in 41ab999c. Call to tpm_chip_put is missing. This
will cause TPM device driver not to unload if tmp_get_random()
is called.

Cc: <stable@vger.kernel.org> # 3.7+
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

drivers/char/tpm/tpm-interface.c

@@ -991,13 +991,13 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
 	int err, total = 0, retries = 5;
 	u8 *dest = out;
 
+	if (!out || !num_bytes || max > TPM_MAX_RNG_DATA)
+		return -EINVAL;
+
 	chip = tpm_chip_find_get(chip_num);
 	if (chip == NULL)
 		return -ENODEV;
 
-	if (!out || !num_bytes || max > TPM_MAX_RNG_DATA)
-		return -EINVAL;
-
 	do {
 		tpm_cmd.header.in = tpm_getrandom_header;
 		tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
@@ -1016,6 +1016,7 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
 		num_bytes -= recd;
 	} while (retries-- && total < max);
 
+	tpm_chip_put(chip);
 	return total ? total : -EIO;
 }
 EXPORT_SYMBOL_GPL(tpm_get_random);