powerpc: Fix missing CRCs, add more asm-prototypes.h declarations

After patch 4efca4ed ("kbuild: modversions for EXPORT_SYMBOL() for asm"),
asm exports can get modversions CRCs generated if they have C definitions
in asm-prototypes.h. This patch adds missing definitions for 32 and 64 bit
allmodconfig builds.

Fixes: 9445aa1a ("ppc: move exports to definitions")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>