sync should clobber memory

Lines 53 to 57 in 48e1ce3

    
           asm volatile("sync %0" 
        
                        :        // no outputs 
        
                        : "n"(0) // heavyweight barrier 
        
                        :        // no clobbers 
        
           );

Like in the linux kernel:

https://github.com/torvalds/linux/blob/edb0a20009363ae787bfe0d6fd52abb504f05113/arch/powerpc/include/asm/barrier.h#L36

Fixed in 004d90b

	asm volatile("sync %0"
	: // no outputs
	: "n"(0) // heavyweight barrier
	: // no clobbers
	);