usb: typec: Check for ops->exit instead of ops->enter in altmode_exit

typec_altmode_exit checks if ops->enter is not NULL but then calls
ops->exit a few lines below. Fix that and check for the function
pointer it's about to call instead.

Fixes: 8a37d87d ("usb: typec: Bus type for alternate modes")
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20221114165924.33487-1-sven@svenpeter.dev


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>