oldland: pass arguments at a zero offset rather than 3 words in.

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Revert "Oldland: don't zero extend sub-word loads."

Revert whilst debugging a u-boot crash that disappears with debugging
prints removed.

This reverts commit b08b1cec4135858957f502d9a61e32319cfde3c5.
oldland: fix varags passing for more than 6 arguments.

The first 6 arguments are passed in registers, the rest need to be
passed by stack.  This works by pushing all register parameters onto the
stack such that they are contiguous with the stack parameters in the
caller.

With this change we don't need the caller to reserve space for registers
that would normally be passed, instead we manually fix the frame and
stack pointers during the prologue computation.