usb: typec: tcpm: fix SOP' sequences in tcpm_pd_svdm

usb: typec: tcpm: fix SOP' sequences in tcpm_pd_svdm

The Smatch checker flags svdm_version being uninitialized for Discover
Identity Messages within tcpm_pd_svdm for the CMDT_INIT case. Cable plugs
cannot initialize SVDM commands, however a port partner that isn't allowed
to communicate over SOP' could, which would result in the CMDT_INIT block
running for a received SOP' message.

First, initialize svdm_version for the TCPC_TX_SOP_PRIME case. If the
svdm_version returns as an error, we expect the received svdm to be the
result of Discover Identity that updates the value accordingly.

Next, drop all SOP' messages of type CMDT_INIT within tcpm_pd_svdm.

Finally, remove redundant call that assigns modep and pdev. Smatch will
raise an uninitialized symbol error over modep_prime and pdev_prime, but
both the assignment and use of these variables are guarded behind
a check for rx_sop_type == TCPC_TX_SOP_PRIME.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/a432603b-b801-4001-b309-247dded707d3@moroto.mountain/
Fixes: fb7ff25ae433 ("usb: typec: tcpm: add discover identity support for SOP'")
Signed-off-by: RD Babiera <rdbabiera@google.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20240223002233.3936275-2-rdbabiera@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>