Disable interrupts while manipulating port mapping control on MSP430, since the port
mapping will forever be read only if the configuration takes more than 32
(assembler) instructions, this is specified in
MSP430x5xx and MSP430x6xx Family User's guide (http://www.ti.com/lit/ug/slau208m/slau208n.pdf),
section "13.2 Port Mapping Controller Operation", page 426

Use PMAPKEYID instead of PMAPPWD, which is deprecated, when setting port mapping password.