x86/microcode_intel.h: Define functions and macros for early loading ucode

Define some functions and macros that will be used in early loading ucode. Some
of them are moved from microcode_intel.c driver in order to be called in early
boot phase before module can be called.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1356075872-3054-3-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>