x86: Clean up the FSP support codes

x86: Clean up the FSP support codes

This is the follow-on patch to clean up the FSP support codes:

- Remove the _t suffix on the structures defines
- Use __packed for structure defines
- Use U-Boot's assert()
- Use standard bool true/false
- Remove read_unaligned64()
- Use memcmp() in the compare_guid()
- Remove the cast in the memset() call
- Replace some magic numbers with macros
- Use panic() when no valid FSP image header is found
- Change some FSP utility routines to use an fsp_ prefix
- Add comment blocks for asm_continuation and fsp_init_done
- Remove some casts in find_fsp_header()
- Change HOB access macros to static inline routines
- Add comments to mention find_fsp_header() may be called in a
  stackless environment
- Add comments to mention init(&params) in fsp_init() cannot
  be removed

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>