[AVR] Implement LPMWRdZ pseudo-instruction's expansion.
[AVR] Implement LPMWRdZ pseudo-instruction's expansion.

FIXME: implementation is mostly copy-pasted from LDWRdPtr, so we should
refactor a bit and unify the two

Patch by Gerdo Erdi.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@314898 91177308-0d34-0410-b5e6-96231b3b80d8

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