cpu/intel/haswell: Allow up to six microcodes in the FIT table

Haswell and Broadwell platforms usually stitch six microcode
patches. It has worked so far with the default value of four thanks a
bug which is being fixed by `util/ifittool: Error out if microcodes do
not fit the FIT table' commit.

BUG=b:245380705
TEST=Jenkins build without failing on the FIT table size

Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Change-Id: I23bf79a3e8918499f6c51e6ef829312d5872181a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67466
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/cpu/intel/haswell/Kconfig

@@ -36,4 +36,7 @@ config SMM_RESERVED_SIZE
 config MAX_CPUS
 	int
 	default 8
+
+config CPU_INTEL_NUM_FIT_ENTRIES
+	default 6
 endif