powerpc: Fix compile of sha1-powerpc-asm.S on 32-bit

When building with CRYPTO_SHA1_PPC enabled we fail with:

powerpc/crypto/sha1-powerpc-asm.S: Assembler messages:
powerpc/crypto/sha1-powerpc-asm.S:116: Error: can't resolve `0' {*ABS* section} - `STACKFRAMESIZE' {*UND* section}
powerpc/crypto/sha1-powerpc-asm.S:116: Error: expression too complex
powerpc/crypto/sha1-powerpc-asm.S:178: Error: unsupported relocation against STACKFRAMESIZE

Use INT_FRAME_SIZE instead of STACKFRAMESIZE.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>