powerpc/pseries: Optimise hcall tracepoints

Now that we execute the hcall tracepoint entry and exit code out of
line, we can use the same stack across both functions.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --cc arch/powerpc/platforms/pseries/hvCall.S
Simple merge