[POWERPC] Xilinx: hwicap cleanup

This fixes various items pointed out during a review of the hwicap driver.
Primarily, reversed memcpy calls, re-entrancy issues, and mutex conversion
have been addressed.  There are also fixes to comments to use the kerneldoc
format, as well as some sparse annotations.

Signed-off-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>