usb: typec: altmodes/displayport: do not index invalid pin_assignments

In the Linux kernel, the following vulnerability has been resolved:

usb: typec: altmodes/displayport: do not index invalid pin_assignments

A poorly implemented DisplayPort Alt Mode port partner can indicate

that its pin assignment capabilities are greater than the maximum

value, DP_PIN_ASSIGN_F. In this case, calls to pin_assignment_show

will cause a BRK exception due to an out of bounds array access.

Prevent for loop in pin_assignment_show from accessing

invalid values in pin_assignments by adding DP_PIN_ASSIGN_MAX

value in typec_dp.h and using i < DP_PIN_ASSIGN_MAX as a loop

condition.