KVM: x86 emulator: Eliminate compilation warning in x86_decode_insn()

Eliminate:
arch/x86/kvm/emulate.c:801: warning: ‘sv’ may be used uninitialized in this
function

on gcc 4.1.2
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/emulate.c

@@ -798,7 +798,7 @@ static int decode_abs(struct x86_emulate_ctxt *ctxt,
 
 static void fetch_bit_operand(struct decode_cache *c)
 {
-	long sv, mask;
+	long sv = 0, mask;
 
 	if (c->dst.type == OP_MEM && c->src.type == OP_REG) {
 		mask = ~(c->dst.bytes * 8 - 1);