[RFC V4 1/3] add CONFIG_HAVE_ARCH_BITREVERSE to support rbit instruction

[Wang, Yalin]

> From: Joe Perches [mailto:joe at perches.com]
> > We also change byte_rev_table[] to be static, to make sure no drivers
> > can access it directly.
> 
> You break the build with this patch.
> 
> You can't do this until the users of the table are converted.
> 
> So far, they are not.
> 
> I submitted patches for these uses, but those patches are not yet applied.
> 
> Please make sure the dependencies for your patches are explicitly stated.
> 
Oh,  byte_rev_table[] must be extern,
Otherwise, bitrev8() can't access it ,
I will change it.