Apparently whoever did these didn't get the gcc docs and specified
every operand only as input, and then added volatile, explicit
initialization and what not until it worked. Specify output operands
correctly instead.
I couldn't verify all assembler variants, as I don't know them,
but the ones I don't know had at least some proper usage of output
operands, so I'll assume those are all correct.

Change-Id: I2910308b5e00cce8db756496df50ed26cfe35bb6