powerpc: Define and use PPC64_ELF_ABI_v2/v1

We're approaching 20 locations where we need to check for ELF ABI v2.
That's fine, except the logic is a bit awkward, because we have to check
that _CALL_ELF is defined and then what its value is.

So check it once in asm/types.h and define PPC64_ELF_ABI_v2 when ELF ABI
v2 is detected.

We also have a few places where what we're really trying to check is
that we are using the 64-bit v1 ABI, ie. function descriptors. So also
add a #define for that, which simplifies several checks.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/kvm/book3s_interrupts.S b/arch/powerpc/kvm/book3s_interrupts.S
index d044b8b..901e6fe 100644
--- a/arch/powerpc/kvm/book3s_interrupts.S
+++ b/arch/powerpc/kvm/book3s_interrupts.S
@@ -25,7 +25,7 @@
 #include <asm/exception-64s.h>
 
 #if defined(CONFIG_PPC_BOOK3S_64)
-#if defined(_CALL_ELF) && _CALL_ELF == 2
+#ifdef PPC64_ELF_ABI_v2
 #define FUNC(name) 		name
 #else
 #define FUNC(name) 		GLUE(.,name)