char: tpm: Kconfig: remove bad i2c cr50 select

This fixes a minor bug which went unnoticed during the initial
driver upstreaming review: TCG_CR50 does not exist in mainline
kernels, so remove it.

Fixes: 3a253caa

 ("char: tpm: add i2c driver for cr50")
Cc: stable@vger.kernel.org
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>