patch for gas error message

[Richard Earnshaw]

> The error message that ARM GAS gives for a bad `msr' instruction is rather 
> ambiguous.  Is this patch OK?
> 
> p.
> 
> 2000-09-01  Theo Honohan  <th@futuretv.com>
> 
> 	* config/tc-arm.c (do_msr): Improve error message. 
> 

Seems fine to me.

R.