[SeaBIOS] expecting string instruction after `rep' with latest SeaBIOS

[Ian Campbell]

Building the seabios defconfig on a 64-bit Debian Wheezy system I'm
seeing:

  Compiling (16bit) out/romlayout.o
src/romlayout.S: Assembler messages:
src/romlayout.S:285: Error: expecting string instruction after `rep'
make: *** [out/romlayout.o] Error 1

That line is:
                // Acquire lock and take ownership of shared stack
        1:      rep nop
        
I've also checked the preprocessed version and the nop isn't being
disappeared or anything like that.

This is with 083ee297ef88d "ohci: Update usb command timeouts to use
usb_xfer_time()". I don't see it with the rel-1.7.5 tag.

git bisect has fingered 0673b7870063a ""smp: Replace QEMU SMP init
assembler code with C; run only in 32bit mode.", which makes sense since
it made those additions to romlayout.S

Other than a compiler bug I can't think what might be going on. Debian
Wheezy has gcc 4.7.2 and binutils 2.22.

Ian.