NXP put "R" as the first name of some pins, e.g., R/PIO1_2/AD3/CT32B1_MAT
This is meant to indicate that it may have a possible extra function
which doesn't exist in the present implementation.
The whole concept seems bogus. First of all, there are several pins with
supposedly different roles but all with a common name. Second, one isn't
even supposed to set the pin configuration register to a value selecting
this "reserved" function. Third, there are several other pins that also
have unused codepoints in their function settings, e.g., PIO0_3 or
PIO0_4/SCL but there's no "R" in evidence there.
So that "R" doesnt seem to make any sense, may cause confusion, and
makes the symbol more crowded.
