samr30 is the only MCU of this family where the vendor files do not
define the PIN_($pin)_EIC_EXTINT_NUM macro yet.
This macro is needed to create a generic EXTI configuration for all
sam0 MCUs.
The defines were generated with
sed -Ei '/define PIN_(.*)_EIC_EXTINT([0-9]*)/
{h; x;
s/define PIN_(.*)A_EIC_EXTINT([0-9]*)(.*)/
define PIN_\1A_EIC_EXTINT_NUM _L_\(\2\)
\/**< \brief EIC signal: PIN_\1 External Interrupt Line *\/
/g; G}' samr30g18a.h samr30e18a.h
93d536f761