powerpc/lib/sstep: Use l1_dcache_bytes() instead of opencoding

Don't opencode dcache size retrieval based on whether that's ppc32 or ppc64.

Use l1_dcache_bytes()
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/6c608fd4795e2d8ea1a0a449405a0087f76d8bb3.1642752375.git.christophe.leroy@csgroup.eu

arch/powerpc/lib/sstep.c

@@ -1065,14 +1065,11 @@ static int __emulate_dcbz(unsigned long ea)
 int emulate_dcbz(unsigned long ea, struct pt_regs *regs)
 {
 	int err;
-	unsigned long size;
+	unsigned long size = l1_dcache_bytes();
 
 #ifdef __powerpc64__
-	size = ppc64_caches.l1d.block_size;
 	if (!(regs->msr & MSR_64BIT))
 		ea &= 0xffffffffUL;
-#else
-	size = L1_CACHE_BYTES;
 #endif
 	ea &= ~(size - 1);
 	if (!address_ok(regs, ea, size))