Revert "[Cmm Sized] Adjust"

In old GHC:

I8# :: Int# -> Int8
indexInt8OffAddr# :: Addr# -> Int# -> Int#
...

In upcoming GHC 9.2:

I8# :: Int8# -> Int8
indexInt8OffAddr# :: Addr# -> Int# -> Int8#
...

Both of those work with the last array release, where the only requirement is merely that the constructor and primops agree, i.e.:

exists alpha.
I8# :: alpha -> Int8
indexInt8OffAddr# :: Addr# -> Int# -> alpha

In current GHC HEAD, we had

I8# :: Int8# -> Int8
indexInt8OffAddr# :: Addr# -> Int# -> Int#

and it was only because Int8# /= Int# that we needed the commit being reverted. we are about to fix the primops to match the constructors in accordance with the final 9.2 design, and so we don't need that commit anymore.

This reverts commit c7a696e3.