tpm: fix spelling

Fix following checkpatch.pl issues in TPM-related code:

    CHECK: '<x>' may be misspelled - perhaps '<y>'?

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>