replaced call to ti.LoadDEInd_s since A could be clobbered

[ZERICO2005]

This appears to be the implementation used for ti.LoadDEInd_s which preserves A:

ti.LoadDEInd_s:
ld de, 0
ld e, (hl)
inc hl
ld d, (hl)
inc hl

However, ti.LoadHLInd_s destroys A despite being a similar routine, this indicates that a future version of ti.LoadDEInd_s may destroy A, so I have inlined the call to prevent A from being destroyed.