tpm: remove superfluous check in tpm_tis_send()

Checking if variable chip is NULL after dereferencing it makes no sense.
As discribed in [1] it is not expected that the variable can ever be NULL.

[1] Re: [PATCH] tpm: avoid NULL pointer dereference in tpm_tis_send()
    https://lore.kernel.org/u-boot/YaFwDtKKYRr7qzWc@apalos.home/

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

drivers/tpm/tpm2_tis_core.c

@@ -224,9 +224,6 @@ int tpm_tis_send(struct udevice *dev, const u8 *buf, size_t len)
 	u8 status;
 	int ret;
 
-	if (!chip)
-		return -ENODEV;
-
 	ret = tpm_tis_request_locality(dev, 0);
 	if (ret < 0)
 		return -EBUSY;