copy/paste bug checking X86_FEATURE_MSR on msr_batch open

[rountree]

Similar to #117 msr_open() in msr_batch.c assumes the minor device number is a cpu and checks if msrs are supported on that cpu. This has been working inadvertently until now.

This is separate from #117 in that we may well want to do a X86_FEATURE_MSR check, but it needs to be moved into where we parse the msr_batch_op array.

Here's the code.

static int msrbatch_open(struct inode *inode, struct file *file)
{
    unsigned int cpu;
    struct cpuinfo_x86 *c; 

    cpu = iminor(file->f_path.dentry->d_inode);
...
    c = &cpu_data(cpu);
    if (!cpu_has(c, X86_FEATURE_MSR))
    {   
        pr_debug("cpu #%u does not have MSR feature.\n", cpu);
        return -EIO; // MSR not supported
    }