tools: use '__i386__' and '__x86_64__' to replace PSR macros

tools: use '__i386__' and '__x86_64__' to replace PSR macros

The libxl interfaces and related functions are not necessary to be included by
'LIBXL_HAVE_PSR_CMT' and 'LIBXL_HAVE_PSR_CAT'. So replace them to common x86
macros. Furthermore, only compile 'xl_psr.c' under x86.

Suggested-by: Roger Pau Monné <roger.pau@citrix.com>
Suggested-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>