Disable interrupts while manipulating port mapping control on MSP430
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/slau208n/slau208n.pdf),
section "13.2 Port Mapping Controller Operation", page 426.
Therefore we disable interrupts while manipulating the port mapping control registers

Use PMAPKEYID instead of PMAPPWD, which is deprecated, when setting port mapping password.
Merge pull request #397 from alfh/feature_pmap_nointerrupt

Disable interrupts while manipulating port mapping control on MSP430