psm: Skip sync check when PSM_CONFIG_NOCHECKSYNC is set

In psmprobe(), we set the initial syncmask to the vendor default value
if the PSM_CONFIG_NOCHECKSYNC bit is unset. However, we currently only
set it for the Elantech touchpad later in psmattach(), thus syncmask
is always configured.

Now, we check PSM_CONFIG_NOCHECKSYNC and skip sync check if it is set.
This fixes Elantech touchpad support for units which have hascrc set.

To clarify that, when we log the syncmask and syncbits fields, also
mention if they are actually used.

Finally, when we set PSM_CONFIG_NOCHECKSYNC, clear PSM_NEED_SYNCBITS
flag.

PR: 225338
MFC after: 1 week