tpm: add macros to enhance TPM commands readability

TPM commands are much easier to read/write with these macros that will
transform words or integers into byte strings. This way, there is no
need to call pack_byte_string() while all variable length in a command
are known (and at must 4 bytes, which is a lot of them).

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