x86: a few optimizations to psr codes

x86: a few optimizations to psr codes

This patch refines psr codes:
1. Change type of 'cat_init_feature' to 'bool' to remove the pointless
   returning of error code.
2. Move printk in 'cat_init_feature' to reduce a return path.
3. Define a local variable 'feat_mask' in 'psr_cpu_init' to reduce calling of
   'cpuid_count_leaf()'.
4. Change 'PSR_INFO_IDX_CAT_FLAG' to 'PSR_INFO_IDX_CAT_FLAGS'.

Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>