boards: update generation comments for NXP board pinctrl files

Update generation comment for NXP board pin control files, to point
users to the current pin control scripting files in NXP's HAL. Note that
these files have not been regenerated- the script name simply has
changed, so update these references to avoid confusion.

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>