KVM: Drop bogus x86_decode_insn() error check

x86_decode_insn() doesn't return X86EMUL_* values, so the check
for X86EMUL_PROPOGATE_FAULT will always fail.  There is a proper
check later on, so there is no need for a replacement for this
code.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>