Fix microcode selection code

The ARM CPUs we know of don't have CPU microcode updates,
so don't show the selection in Kconfig.

Also simplify (and fix) the microcode selection in the Makefile
that would try to include microcode even though none is available.

Change-Id: I502d9b48d4449c1a759b5e90478ad37eef866406
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/2540
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)
2 files changed