powerpc/ps3: lv1 hcall code use symbolic constant for LR save offset

The LRSAVE constant is required for assembly compiled for both 32-bit
and 64-bit, because the value differs there. PS3 is 64-bit only so
this is a noop, but it is nice to abstract stack frame offsets.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231227072405.63751-3-npiggin@gmail.com