msp430: do not read destination operand for MOV #63

Job	Run time
ci / Build	3m 15s
ci / Lint	57s
ci / Test (0)	1m 12s
ci / Test (1)	1m 9s
ci / Test (2)	1m 19s
ci / Test (3)	56s
ci / Test (4)	1m 40s
ci / Test (5)	55s
ci / Test (6)	54s
ci / Test (7)	52s
ci / Test (8)	58s
ci / Test (9)	1m 40s
ci / Publish Unit Tests Results	1s
	15m 48s

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