powerpc/64s: Rename EXCEPTION_RELON_PROLOG_PSERIES_1

The EXCEPTION_RELON_PROLOG_PSERIES_1() macro does the same job as
EXCEPTION_PROLOG_2 (which we just recently created), except for
"RELON" (relocation on) exceptions.

So rename it as such.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>