Silence compiler warning in arch/x86/kvm/emulate.c

Compiler warning:

 CC [M]  arch/x86/kvm/emulate.o
arch/x86/kvm/emulate.c: In function "__do_insn_fetch_bytes":
arch/x86/kvm/emulate.c:814:9: warning: "linear" may be used uninitialized in this function [-Wmaybe-uninitialized]

GCC is smart enough to realize that the inlined __linearize may return before
setting the value of linear, but not smart enough to realize the same
X86EMU_CONTINUE blocks actual use of the value.  However, the value of
'linear' can only be set to one value, so hoisting the one line of code
upwards makes GCC happy with the code.

Reported-by: Aruna Hewapathirane <aruna.hewapathirane@gmail.com>
Tested-by: Aruna Hewapathirane <aruna.hewapathirane@gmail.com>
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>